Please check whether you didn't change the Silverlight settings in VSExtensions Options from the Telerik menu item in Vusual Studio - I've attached a screenshot to show you the settings.
Also you can use our Upgrade Wizard, please check here
for more details.
the Telerik team
Sharpen your .NET Ninja skills
! Attend Q1 webinar week and get a chance to win a license! Book your seat now >>