We would like to restrict two answers in a question: the response ER04-01 of question ER04 should be greater than ER04-02. We applied the following code in the "PHP for Processing Responses" section:
php
$val1 = value('E04_01');
$val2 = value('E04_02');
if (is_numeric($val1) && is_numeric($val2)) {
if ($val1 <= $val2) {
stopPage("Drug (%) must be greater than Placebo (%). Please correct your input.");
}
}
However, the system keeps showing the following warning:
Warning: The funktion stopPage() is not known.
Attachment is the page screenshot.
Could you please help us figure out the issue or show us the correct way to implement this code?
Thank you very much for your support.