Thank you for using our services.
You will get this kind of message if the version of the RadControls for ASP.NET AJAX in the SitefinityWebApplication project is not the same as the project has been built against. The Sitefinity 4.0 Public CTP uses Telerik.Web.UI assembly version 2010.1.309.35. If this has been changed in your project you will experience these problems. Please check your references and make sure that the reference is pointing at the version mentioned above. You might have to revert to the controls the web application is shipped with, if you have upgraded them.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items.