Alright i had inserted Progress bar ever since that it is causing problem.
I removed following:
<div id="formstep21_ProgressMessageWrapper" class="blockUIOverlay" style="display:none;">
<script type="text/javascript">
WADFP_SetProgressToForm('formstep21', 'formstep21_ProgressMessageWrapper', WADFP_Theme_Options['BigSpin:Slate']);
</script>
<div id="formstep21_ProgressMessage" >
<p style="margin:10px; padding:5px;" ><img src="../webassist/progress_bar/images/slate-largespin.gif" alt="" title="" style="vertical-align:middle;" /> Please wait</p>
</div>
Then form works. but i do require progress bar here.