This is a Visual Studio issue and not a C# issue. This question is better suited for the Microsoft Q&A
forums.
The error you're getting indicates the control(s) you're trying to use don't support the platform you're targeting. This is a question for the third party library you're trying to use so you'll need to ask them. They may not support WPF and/or the version
of the .NET framework you're using. Only they can answer that.
Michael Taylor http://www.michaeltaylorp3.net