Hi

The link is survey.stjobs.sg

Sometimes the survey works, sometimes the survey keep showing question is mandatory even though answer is valid.

Please help asap.

First of all two things off topic
1. very nice template.
2. from a research point of view there are quite a few questions that shouldn't be asked the way they are, because you are skewing results through the way you ask.

Now to your actual problem:
I went through the questionnaire and couldn't find any problems, but then I also answered all questions.

In which questions does this problem appear?

Do the problems also appear in one of the standard templates?