How can I add a .NET assembly into a Windows Phone SDK project and use it

Hi guys!

I'm using Visual Studio 2012 with Windows Phone SDK. I have built a mobile application using it. I also used MATLAB 2014a to build a .NET assembly.

I now need to use this assembly in my Visual Studio project.

When I try adding the assembly into my project an error message keeps popping up saying "A reference to a higher version or incompatible assembly cannot be added to the project".

Help?

Thanks in advance.