Millisecond Forums

Hi,
I am putting together an experiment that is a variation of the digit span memory task.
Participants are presented with a 4-digit number, and have to enter the digits in a text box, but replace all 1s with 9s and 5s with 8s. (so if they see 2343, they would enter 2343, but if they see 2345 they would enter 2348)
I want to evaluate whether participants got the correct answer on each trial, but am running into some problems. 

Here is some of the syntax I use (I could send you the full syntax if you want)

<expressions>
/fullnumber = evaluate (text.digit1.currentitem*1000 + text.digit2.currentitem*100 + text.digit3.currentitem*10 +text.digit4.currentitem)
/d1 = values.d1
/d2 = values.d2
/d3 = values.d3
/d4 = values.d4
/fullcorrect = (values.d1*1000) + (values.d2*100) +(values.d3*10) +values.d4
/correctanswer = values.correctanswer
</expressions>

<openended practice_add3>
/ stimulustimes = [0 = signal; 1000 = eraser; 1100 = digit1 , digit2, digit3, digit4; 3100 = eraser, response]
/ mask = positiveinteger
/ inputdevice = keyboard
/ charlimit = 4
/ size = (15%, 2.5%)
/ validresponse = (anyresponse)
/timeout = 7000
/ontrialend = [if (text.digit1.currentitem !=5 && text.digit1.currentitem !=1) values.d1 = text.digit1.currentitem; if (text.digit1.currentitem ==5) values.d1 = 8; if (text.digit1.currentitem ==1) values.d1 = 9]
/ontrialend = [if (text.digit2.currentitem !=5 && text.digit2.currentitem !=1) values.d2 = text.digit2.currentitem; if (text.digit2.currentitem ==5) values.d2 = 8; if (text.digit2.currentitem ==1) values.d2 = 9]
/ontrialend = [if (text.digit3.currentitem !=5 && text.digit3.currentitem !=1) values.d3 = text.digit3.currentitem; if (text.digit3.currentitem ==5) values.d3 = 8; if (text.digit3.currentitem ==1) values.d3 = 9]
/ontrialend = [if (text.digit4.currentitem !=5 && text.digit4.currentitem !=1) values.d4 = text.digit4.currentitem; if (text.digit4.currentitem ==5) values.d4 = 8; if (text.digit4.currentitem ==1) values.d4 = 9]
/iscorrectresponse = [evaluate (openended.practice_add3.response - expressions.fullcorrect)==0]
/ontrialend = [values.correctanswer = expressions.fullcorrect]
/ontrialend = [if (openended.practice_add3.correct == true) values.numcorrectadd3practice = values.numcorrectadd3practice + 1]
/ buttonlabel = "Press CTRL+ENTER to continue"
/ errormessage = true(error,400)
/correctmessage = true(yescorrect, 400)
</openended>

digit1 through digit4 are randomly generated digits. I know the program is correctly recording the presented numbers, what should be the 'correct' response, and the response I input (because I ask for the relevant expressions to be saved in the output file), but it is not recognizing correct responses as being correct, so I think my problem is with the /iscorrectresponse line.

I also tried the following:
 /iscorrectresponse = [openended.practice_add3.response == expressions.fullcorrect]
and that does not work either.

Any other suggestions would be appreciated!