UNetWeaver error and StreamSocket

Hello.
A got an build error: UNetWeaver error: Exception :Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: 'Windows.Foundation.UniversalApiContract, Version=3.0.0.0, Culture=neutral, PublicKeyToken=null' . Build failed. It occurred when I declare StreamSocket variable:
private StreamSocket streamSocket;
Error also happens when I use dll with declared StreamSocket as member, mentioned above.
But, when I use local declaration, there is now errors. But in this case, I think socket object collecting and destoying in time by gc. Thats why my connection broke. Help ASAP, please.

P.S. Also after build error, I need to restart IDE after fix problem. Sounds not good (