I have responded to your other tickets. Unfortunately I could not reproduce the problem with the information at hand. In general extension methods are supported just fine, we have quite a lot of test solutions where JC does not report any false errors for them. So there must be something special in your solution. Now it would be great if you could help us to figure out what that is. The best and in many cases only way to do that is trying to produce a sample solution which demonstrates the problem.
We would also be willing to look at your whole solution if you are comfortable with sending it to us.
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? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items.