Question ID for second question is 12003. LEMval12003 is called three times when validating this question. but third time, jsName is "java757229X761X12002", and 12002 is the ID of the previous question. sdatetimePattern is undefined third time.

Function LEMval from em_javacript.js is used to validate.

Another problem: When running survey group by group, second datepicker won't work because of a JS error:

Uncaught TypeError: minDate() Could not parse date parameter: {d1.NAOK}

This line in qandas return null, even when $date_min = 'd1.NAOK'.

918: $date_time_em = strtotime(LimeExpressionManager::ProcessString("{".$date_min."}",$ia[0]));

But only when running group-by-group.

FYI, it works in 2.06lts to run it group-by-group. The validation is correct, even when calculated dynamically.

Running

LEMval('d1.NAOK')

in the console on the second page returns a date in 2.06lts, but 'Invalid date' in 2.5.

@aestu work hard to have a functionnal way with jquery-ui date ... but we quit jquery-ui date ....

Maybe he can have some advice (he was the DEV about all of this)

Please pull and test, Mazi.

There's still an issue where it's possible to submit wrong date, question-by-question.

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=21018

Version 2.54.4 released