Thank you for contacting us.
As it turns out, the error you are getting is too general to determine what went wrong in your application.
We've recently fixed a design time exception for Silverlight in our latest internal build.
However I might not be sure, whether we are talking about similar thing.
Do you get exceptions at runtime?
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.