Hi ahiresh,

Are you trying to run a CLR 2.0 or CLR 3.5 website.  It looks like in the design time error, it cannot find Ajax extensions 1.0.  Have you installed them?  They can be found in your infragistics install directory.  Also, make sure you only have one version of the web extensions referenced.  the 1.0 version or 3.5.  Let me know if you require further assistance or can provide more information.

regards,
David Young