.NET framework version issue

[sonu]

Hi,

I have upgraded my machine to .NET framework new version.
I have an ASP.NET application which is built using the
previous version. I have pointed my asp.net app to use the
older version (setting in the IIS). But when i execute the
application, it provides error in one of the validation
controls in one aspx page. All of my aspx pages have
validation controls and all of them are working fine.
Except one validation control in one aspx page. That
validation control is a custon validation control.

Can some one tell whats the issue???

Thanks
Sonu