﻿<?xml version="1.0" encoding="UTF-8"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/"><channel><title>Millisecond Forums » Millisecond Forums » Inquisit 5  » list.mylist.nextvalue causes strange errors: Expression 'text' is invalid. Expression contains an unknown element or property name.</title><generator>InstantForum 2017-1 Final</generator><description>Millisecond Forums</description><link>https://forums.millisecond.com/</link><webMaster>Millisecond Forums</webMaster><lastBuildDate>Fri, 25 Sep 2026 16:17:53 GMT</lastBuildDate><ttl>20</ttl><item><title>list.mylist.nextvalue causes strange errors: Expression 'text' is invalid. Expression contains an unknown element or property name.</title><link>https://forums.millisecond.com/Topic28162.aspx</link><description>I build a list, like so:&lt;br/&gt;&lt;br/&gt;[code]&amp;lt;list category1&amp;gt;&lt;br/&gt;/ items = ("01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15", "16")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list category2&amp;gt;&lt;br/&gt;/ items = ("17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list catalogue&amp;gt;&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;values listbuilder&amp;gt;&lt;br/&gt;/ delaytype = -1&lt;br/&gt;/ ct = 0&lt;br/&gt;/ ct2 = 0&lt;br/&gt;/ tester = "..."&lt;br/&gt;&amp;lt;/values&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;block listbuilder&amp;gt;&lt;br/&gt;/ trials = [1=listbuilder]&lt;br/&gt;&amp;lt;/block&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;trial listbuilder&amp;gt;&lt;br/&gt;/ ontrialbegin = [&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.delaytype+=1;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.ct+=1;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;if(values.delaytype==4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.delaytype=0;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"F"),list.category1.nextvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"O"),list.category2.nextvalue))&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}else{&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"F"),list.category1.currentvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"O"),list.category2.currentvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}&lt;br/&gt;]&lt;br/&gt;/ timeout=0&lt;br/&gt;/ branch=[&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;if(values.ct &amp;lt; 16*4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;trial.listbuilder&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}&lt;br/&gt;]&lt;br/&gt;&amp;lt;/trial&amp;gt;[/code]&lt;br/&gt;&lt;br/&gt;However, any subsequent call to list.catalogue.nextvalue causes an error and does not provide the next value. It says: &lt;br/&gt;&lt;br/&gt;&lt;span id="if_insertedNode_1579872812404"&gt;[quote]element: list.catalogue&lt;br/&gt;attribute: nextvalue&lt;br/&gt;message: Expression '2F10' is invalid. Expression contains an unknown element or property name.[/quote]&lt;/span&gt;&lt;br/&gt;&lt;br/&gt;&lt;br/&gt;It seems like Inquisit is trying to parse the list item... but I merely want to assign the item as a string to a variable. What should I do?&lt;br/&gt;</description><pubDate>Mon, 27 Jan 2020 08:34:22 GMT</pubDate><dc:creator>Sercan</dc:creator></item><item><title>RE: list.mylist.nextvalue causes strange errors: Expression 'text' is invalid. Expression contains an unknown element or property name.</title><link>https://forums.millisecond.com/Topic28167.aspx</link><description>&lt;blockquote data-id="28163" class="if-quote-wrapper" unselectable="on" data-guid="1580114056095" id="if_insertedNode_1580114054784" contenteditable="false"&gt;&lt;a class="quote-para" unselectable="on" style="display: none;" href="#" data-id="28163" title="Move Cursor Below" contenteditable="false"&gt;&lt;span unselectable="on"&gt;+&lt;/span&gt;&lt;/a&gt;&lt;a class="quote-delete" unselectable="on" style="display: none;" href="#" data-id="28163" title="Delete Quote" contenteditable="false"&gt;&lt;span unselectable="on"&gt;x&lt;/span&gt;&lt;/a&gt;&lt;span unselectable="on" class="quote-markup"&gt;[quote]&lt;/span&gt;&lt;div unselectable="on" class="if-quote-header" contenteditable="false"&gt;&lt;div unselectable="on" class="if-quote-toggle-wrapper"&gt;&lt;a class="if-quote-toggle quote-link" href="#" data-id="28163" title=" "&gt;&amp;nbsp;&lt;/a&gt;&lt;/div&gt;&lt;span unselectable="on" class="quote-markup"&gt;[b]&lt;/span&gt;Dave - 1/24/2020&lt;span unselectable="on" class="quote-markup"&gt;[/b]&lt;/span&gt;&lt;/div&gt;&lt;div class="if-quote-message if-quote-message-28163"&gt;&lt;div class="if-quote-message-margin" contenteditable="true"&gt;&lt;blockquote data-id="28162" class="if-quote-wrapper" unselectable="on" data-guid="1580114056095" id="if_insertedNode_1579881916117" contenteditable="false"&gt;&lt;a class="quote-para" unselectable="on" style="display: none;" href="#" data-id="28162" title="Move Cursor Below" contenteditable="false"&gt;&lt;span unselectable="on"&gt;+&lt;/span&gt;&lt;/a&gt;&lt;a class="quote-delete" unselectable="on" style="display: none;" href="#" data-id="28162" title="Delete Quote" contenteditable="false"&gt;&lt;span unselectable="on"&gt;x&lt;/span&gt;&lt;/a&gt;&lt;span unselectable="on" class="quote-markup"&gt;[quote]&lt;/span&gt;&lt;div unselectable="on" class="if-quote-header" contenteditable="false"&gt;&lt;div unselectable="on" class="if-quote-toggle-wrapper"&gt;&lt;a class="if-quote-toggle quote-link" href="#" data-id="28162" title=" "&gt;&amp;nbsp;&lt;/a&gt;&lt;/div&gt;&lt;span unselectable="on" class="quote-markup"&gt;[b]&lt;/span&gt;Sercan - 1/24/2020&lt;span unselectable="on" class="quote-markup"&gt;[/b]&lt;/span&gt;&lt;/div&gt;&lt;div class="if-quote-message if-quote-message-28162"&gt;&lt;div class="if-quote-message-margin" contenteditable="true"&gt;I build a list, like so:&lt;br/&gt;&lt;br/&gt;[code]&amp;lt;list category1&amp;gt;&lt;br/&gt;/ items = ("01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15", "16")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list category2&amp;gt;&lt;br/&gt;/ items = ("17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list catalogue&amp;gt;&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;values listbuilder&amp;gt;&lt;br/&gt;/ delaytype = -1&lt;br/&gt;/ ct = 0&lt;br/&gt;/ ct2 = 0&lt;br/&gt;/ tester = "..."&lt;br/&gt;&amp;lt;/values&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;block listbuilder&amp;gt;&lt;br/&gt;/ trials = [1=listbuilder]&lt;br/&gt;&amp;lt;/block&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;trial listbuilder&amp;gt;&lt;br/&gt;/ ontrialbegin = [&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.delaytype+=1;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.ct+=1;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;if(values.delaytype==4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.delaytype=0;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"F"),list.category1.nextvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"O"),list.category2.nextvalue))&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}else{&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"F"),list.category1.currentvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"O"),list.category2.currentvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}&lt;br/&gt;]&lt;br/&gt;/ timeout=0&lt;br/&gt;/ branch=[&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;if(values.ct &amp;lt; 16*4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;trial.listbuilder&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}&lt;br/&gt;]&lt;br/&gt;&amp;lt;/trial&amp;gt;[/code]&lt;br/&gt;&lt;br/&gt;However, any subsequent call to list.catalogue.nextvalue causes an error and does not provide the next value. It says: &lt;br/&gt;&lt;br/&gt;&lt;span id="if_insertedNode_1579872812404"&gt;[quote]element: list.catalogue&lt;br/&gt;attribute: nextvalue&lt;br/&gt;message: Expression '2F10' is invalid. Expression contains an unknown element or property name.[/quote]&lt;/span&gt;&lt;br/&gt;&lt;br/&gt;&lt;br/&gt;It seems like Inquisit is trying to parse the list item... but I merely want to assign the item as a string to a variable. What should I do?&lt;br/&gt;&lt;a class="if-quote-goto quote-link" href="#" data-id="28162"&gt;&lt;span class="goto"&gt;&lt;/span&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt;&lt;span unselectable="on" class="quote-markup"&gt;[/quote]&lt;/span&gt;&lt;/blockquote&gt;&lt;br/&gt;The problem is the mixing of different data types -- integers (values.delaytype) and string literals "O" and "F". Due to the order of operations in your nested concat() statements, the resulting value will attempt to be interpreted as a numerical value, which it actually isn't. The solution is to effectively cast the value to a string data type by enclosing it in quotes. &lt;br/&gt;&lt;br/&gt;I've separated it into steps below for clarity:&lt;br/&gt;&lt;br/&gt;&amp;lt;list category1&amp;gt;&lt;br/&gt;/ items = ("01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15", "16")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list category2&amp;gt;&lt;br/&gt;/ items = ("17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list catalogue&amp;gt;&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;values listbuilder&amp;gt;&lt;br/&gt;/ delaytype = -1&lt;br/&gt;/ ct = 0&lt;br/&gt;/ ct2 = 0&lt;br/&gt;/ item = ""&lt;br/&gt;/ tester = "..."&lt;br/&gt;&amp;lt;/values&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;block listbuilder&amp;gt;&lt;br/&gt;/ trials = [1=listbuilder; 2-129=mytrial]&lt;br/&gt;&amp;lt;/block&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;trial listbuilder&amp;gt;&lt;br/&gt;/ ontrialbegin = [&lt;br/&gt;&amp;nbsp; values.delaytype+=1;&lt;br/&gt;&amp;nbsp; values.ct+=1;&lt;br/&gt;&amp;nbsp; if(values.delaytype==4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;  values.delaytype=0;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"F"),list.category1.nextvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"O"),list.category2.nextvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp; }else{&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"F"),list.category1.currentvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"O"),list.category2.currentvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp; }&lt;br/&gt;]&lt;br/&gt;/ timeout=0&lt;br/&gt;/ branch=[&lt;br/&gt;&amp;nbsp; if(values.ct &amp;lt; 16*4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;  trial.listbuilder&lt;br/&gt;&amp;nbsp; }&lt;br/&gt;]&lt;br/&gt;&amp;lt;/trial&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;trial mytrial&amp;gt;&lt;br/&gt;/ ontrialbegin = [&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = "";&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = list.catalogue.nextvalue;&lt;br/&gt;]&lt;br/&gt;/ stimulusframes = [1=mytext]&lt;br/&gt;/ validresponse = (57)&lt;br/&gt;&amp;lt;/trial&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;text mytext&amp;gt;&lt;br/&gt;/ items = ("&amp;lt;%values.item%&amp;gt;")&lt;br/&gt;&amp;lt;/text&amp;gt;&lt;br/&gt;&lt;br/&gt;&lt;br/&gt;&lt;a class="if-quote-goto quote-link" href="#" data-id="28163"&gt;&lt;span class="goto"&gt;&lt;/span&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt;&lt;span unselectable="on" class="quote-markup"&gt;[/quote]&lt;/span&gt;&lt;/blockquote&gt;&lt;br/&gt;That worked. Thanks!</description><pubDate>Mon, 27 Jan 2020 08:34:22 GMT</pubDate><dc:creator>Sercan</dc:creator></item><item><title>RE: list.mylist.nextvalue causes strange errors: Expression 'text' is invalid. Expression contains an unknown element or property name.</title><link>https://forums.millisecond.com/Topic28163.aspx</link><description>&lt;blockquote data-id="28162" class="if-quote-wrapper" unselectable="on" data-guid="1579881916801" id="if_insertedNode_1579881916117" contenteditable="false"&gt;&lt;a class="quote-para" unselectable="on" style="display: none;" href="#" data-id="28162" title="Move Cursor Below" contenteditable="false"&gt;&lt;span unselectable="on"&gt;+&lt;/span&gt;&lt;/a&gt;&lt;a class="quote-delete" unselectable="on" style="display: none;" href="#" data-id="28162" title="Delete Quote" contenteditable="false"&gt;&lt;span unselectable="on"&gt;x&lt;/span&gt;&lt;/a&gt;&lt;span unselectable="on" class="quote-markup"&gt;[quote]&lt;/span&gt;&lt;div unselectable="on" class="if-quote-header" contenteditable="false"&gt;&lt;div unselectable="on" class="if-quote-toggle-wrapper"&gt;&lt;a class="if-quote-toggle quote-link" href="#" data-id="28162" title=" "&gt;&amp;nbsp;&lt;/a&gt;&lt;/div&gt;&lt;span unselectable="on" class="quote-markup"&gt;[b]&lt;/span&gt;Sercan - 1/24/2020&lt;span unselectable="on" class="quote-markup"&gt;[/b]&lt;/span&gt;&lt;/div&gt;&lt;div class="if-quote-message if-quote-message-28162"&gt;&lt;div class="if-quote-message-margin" contenteditable="true"&gt;I build a list, like so:&lt;br/&gt;&lt;br/&gt;[code]&amp;lt;list category1&amp;gt;&lt;br/&gt;/ items = ("01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15", "16")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list category2&amp;gt;&lt;br/&gt;/ items = ("17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list catalogue&amp;gt;&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;values listbuilder&amp;gt;&lt;br/&gt;/ delaytype = -1&lt;br/&gt;/ ct = 0&lt;br/&gt;/ ct2 = 0&lt;br/&gt;/ tester = "..."&lt;br/&gt;&amp;lt;/values&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;block listbuilder&amp;gt;&lt;br/&gt;/ trials = [1=listbuilder]&lt;br/&gt;&amp;lt;/block&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;trial listbuilder&amp;gt;&lt;br/&gt;/ ontrialbegin = [&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.delaytype+=1;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.ct+=1;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;if(values.delaytype==4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.delaytype=0;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"F"),list.category1.nextvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"O"),list.category2.nextvalue))&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}else{&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"F"),list.category1.currentvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;list.catalogue.appenditem(concat(concat(values.delaytype,"O"),list.category2.currentvalue));&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}&lt;br/&gt;]&lt;br/&gt;/ timeout=0&lt;br/&gt;/ branch=[&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;if(values.ct &amp;lt; 16*4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;trial.listbuilder&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;}&lt;br/&gt;]&lt;br/&gt;&amp;lt;/trial&amp;gt;[/code]&lt;br/&gt;&lt;br/&gt;However, any subsequent call to list.catalogue.nextvalue causes an error and does not provide the next value. It says: &lt;br/&gt;&lt;br/&gt;&lt;span id="if_insertedNode_1579872812404"&gt;[quote]element: list.catalogue&lt;br/&gt;attribute: nextvalue&lt;br/&gt;message: Expression '2F10' is invalid. Expression contains an unknown element or property name.[/quote]&lt;/span&gt;&lt;br/&gt;&lt;br/&gt;&lt;br/&gt;It seems like Inquisit is trying to parse the list item... but I merely want to assign the item as a string to a variable. What should I do?&lt;br/&gt;&lt;a class="if-quote-goto quote-link" href="#" data-id="28162"&gt;&lt;span class="goto"&gt;&lt;/span&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt;&lt;span unselectable="on" class="quote-markup"&gt;[/quote]&lt;/span&gt;&lt;/blockquote&gt;&lt;br/&gt;The problem is the mixing of different data types -- integers (values.delaytype) and string literals "O" and "F". Due to the order of operations in your nested concat() statements, the resulting value will attempt to be interpreted as a numerical value, which it actually isn't. The solution is to effectively cast the value to a string data type by enclosing it in quotes. &lt;br/&gt;&lt;br/&gt;I've separated it into steps below for clarity:&lt;br/&gt;&lt;br/&gt;&amp;lt;list category1&amp;gt;&lt;br/&gt;/ items = ("01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15", "16")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list category2&amp;gt;&lt;br/&gt;/ items = ("17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32")&lt;br/&gt;/ replace = false&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;list catalogue&amp;gt;&lt;br/&gt;&amp;lt;/list&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;values listbuilder&amp;gt;&lt;br/&gt;/ delaytype = -1&lt;br/&gt;/ ct = 0&lt;br/&gt;/ ct2 = 0&lt;br/&gt;/ item = ""&lt;br/&gt;/ tester = "..."&lt;br/&gt;&amp;lt;/values&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;block listbuilder&amp;gt;&lt;br/&gt;/ trials = [1=listbuilder; 2-129=mytrial]&lt;br/&gt;&amp;lt;/block&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;trial listbuilder&amp;gt;&lt;br/&gt;/ ontrialbegin = [&lt;br/&gt;&amp;nbsp; values.delaytype+=1;&lt;br/&gt;&amp;nbsp; values.ct+=1;&lt;br/&gt;&amp;nbsp; if(values.delaytype==4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;  values.delaytype=0;&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"F"),list.category1.nextvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"O"),list.category2.nextvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp; }else{&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"F"),list.category1.currentvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat(values.delaytype,"O"),list.category2.currentvalue);&lt;br/&gt;&lt;strong&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = concat(concat("~"", values.item), "~"");&lt;/strong&gt;&lt;br/&gt;&amp;nbsp;&amp;nbsp;  list.catalogue.appenditem(values.item);&lt;br/&gt;&amp;nbsp; }&lt;br/&gt;]&lt;br/&gt;/ timeout=0&lt;br/&gt;/ branch=[&lt;br/&gt;&amp;nbsp; if(values.ct &amp;lt; 16*4){&lt;br/&gt;&amp;nbsp;&amp;nbsp;  trial.listbuilder&lt;br/&gt;&amp;nbsp; }&lt;br/&gt;]&lt;br/&gt;&amp;lt;/trial&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;trial mytrial&amp;gt;&lt;br/&gt;/ ontrialbegin = [&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = "";&lt;br/&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;values.item = list.catalogue.nextvalue;&lt;br/&gt;]&lt;br/&gt;/ stimulusframes = [1=mytext]&lt;br/&gt;/ validresponse = (57)&lt;br/&gt;&amp;lt;/trial&amp;gt;&lt;br/&gt;&lt;br/&gt;&amp;lt;text mytext&amp;gt;&lt;br/&gt;/ items = ("&amp;lt;%values.item%&amp;gt;")&lt;br/&gt;&amp;lt;/text&amp;gt;&lt;br/&gt;&lt;br/&gt;&lt;br/&gt;</description><pubDate>Fri, 24 Jan 2020 16:09:25 GMT</pubDate><dc:creator>Dave</dc:creator></item></channel></rss>