Hi Edin,
Most likely you use .NET Framework 4.0 Client Profile - you need to use the regular .NET framework 4.0 - to fix this go to project settings Compile / Advanced Compile Options then from the Target Framework select ".NET Framework 4" (by default it's set to client profile in VS2010, but later this whole version of .NET framework was abandoned. Hope this helps - let us know if the problem persists...