Unable to add existing project (ClientLibrary.csproj) to the solution I build

In the face API, when I add the "ClientLibrary.csproj" to the solution or open the ClientLibrary.csproj directly, there always comes out an error: Unable to open the project file "ClientLibrary". The framework of this project is not installed or as part of the framework of future updates included for visual studio.

I am using visual studio 2013, windows 8.

Any help would be much appreciated.