In the new Visual Studio 2015 RC the XAML designer does not bring up a UI for a C# Windows Universal project but it does for a C++ Windows Universal project. This occurs wi
you have to have the appropriate sdk installed on your machine, you can get it from the official site of Microsoft https://developer.microsoft.com/en-us/windows/downloads/sdk-archive
before that please remove the old sdk you installed on your pc, so that VS will use the new one.
then it'll work... i fixed mine in this way.