Hi venkivenkatesan,
Looks like your binding the value
<%Eval("Regno" )%>
to the querystring value. AS the syntax is incorrect, the compliler is interpreting it as a static value instead of a dynamic value.
There is a missing # part in that scenario, which is causing the issue.
Try this one instead of yours:
<%# Eval("Regno" )%>
Thank you,
Vamsi