<trial examples>
/ stimulusframes = [1=examplestrials, true, false]
/ validresponse = (true, false)
/ correctmessage = (correct, 500)
/ errormessage = (error, 500)
/ iscorrectresponse = [trial.examples.response == getitem(item.exampleanswers,
text.examples.selectedindex)]
</trial>
You determine the correct response based on the selected item for <text examples>. However, you do *not* actually display that <text> element in the <trial> (cf. the /stimulusframes attribute). Hence no selection ever occurs for that element and its selectedindex is useless.
You'll want to do
<trial examples>
/ stimulusframes = [1=
examplestrials, true, false]
/ validresponse = (true, false)
/ correctmessage = (correct, 500)
/ errormessage = (error, 500)
/ iscorrectresponse = [trial.examples.response == getitem(item.exampleanswers,
sound.examplestrials.selectedindex)]
</trial