Sometimes when a mandatory field IS filled with an answer, the error  message still appears that the mandatory question must be answered!

Then people cannot continue the survey.

When you type a space character behind the text it works fine, and the system sees that the mandatory field IS filled.

Any ideas?

It is indeed very strange. And it is even stranger because it does not alway occur. I've just discovered that it only happens when you use the autocomplete function from Internet Explorer 7 and also from Firefox v2.

The first field is a radiobuttonfield. When you go to the second field with the TAB button, which is a textfield, and press the arrow down key, to get a list of previous entered words, the javascript code (I think) does not recognize that there is text in the field.

The only way to get passed this error is to physically enter the text in that field... or to type another character behind yhe autocompleted text.

Link is http://www.trancewerk.nl/enquete.html

(it's in Dutch)