Microsoft.TeamFoundation.WorkItemTracking.Server.Dataaccesslayer.dll reference is not resolving after I upgrade to TFS 2013 Update 2 and Visual Studio Premium Update 2

I had a custom control which was working fine before I upgraded to TFS 2013 Update 2 and VS 2013 Update 2.

But after upgrade it does not work.

When I tried to recompile the code,It throws error that "The tyep or name space does not exist in C:\Program Files\Microsoft Team Foundation Server 12.0\Tools\Plugins\Microsoft.TeamFoundation.WorkItemTracking.Server.Dataaccesslayer.dll"

I have added assembly and it is there in 2-3 more locations. I tried adding from all locations but no luck. The dll is successfully added to references but does not resolve it.

Could you please help me to resolve it?

Thanks,

Anurag