cannot find mscorlib in portable class library

cannot find mscorlib in portable class library

I cannot find mscorlib when I right-click and say 'Add Reference'. I
cannot find any of the core libraries.
I was targeting .net framework 4.0, windows phone and silverlight. This
corresponds to profile 2. On checking the folder, mscorlib is present in
profile 2.
I have installed .Net framework 4.0.3 and 4.5 on my system.
If someone could help me out I would appreciate it.
Sharpi.