I had project in VS2008 with Silverlight 3.0 but when i installed 4.0 and uninstalled 3.0 its not working "Its not loading the project in solution explorer " [I hav installed both SDK and Tool Kit]
A:
I wouldn't recommend uninstall Silverlight 3.0 SDK. In fact installing VS2010 will install Silverlight 3 and its SDK.
My guess is you've upgraded the solution and project files but its still a a Silverlight 3 project, VS2010 is quite happy to support the development of Silverlight 3. With the Silverlight 3 SDK being missing it can't find any of the references it needs.
With the Silveright 4.0 tools installed, go to the Silverlight project's properties Silverlight page and set Target Silverlight Version to "Silverlight 4".
AnthonyWJones
2010-06-09 11:07:01