Regd: TFS Build Issues-targets (1605): Could not resolve this reference

I am facing one issue while triggering the TFS Release build. It seems its expecting the system.web.moles in the Build server. Support Team from Client side tried installing the Moles in the TFS build server but still we are getting the same issue and Build is failing. We are having a Unit test project which triggers during Release build whereas gated Build works fine. Please let me know if you have faced any similar issue. I am checking in the Builds server whether we have any mismatch in version for the dlls.

Please note that we are using TFS 2010 .

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Microsoft.Common.targets (1605): Could not resolve this reference. Could not locate the assembly "System.Web.Moles, Version=4.0.0.0, Culture=neutral, PublicKeyToken=0ae41878053f6703, processorArchitecture=MSIL". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.

m.g.cs (20102): 'Cal.Bsip.MemberPortal.Common.Validation.Moles.SStringNotNullOrEmptyValidatorAttribute.RequiresValidationContext': no suitable method found to override [E:\Builds\2\BSIP\R4.2_Member_Portal_Release_Build\Sources\UnitTests\obj\Release\Moles\cbmpc\m.g.csproj]

m.g.cs (20102): 'Cal.Bsip.MemberPortal.Common.Validation.Moles.SStringNotNullOrEmptyValidatorAttribute.RequiresValidationContext': no suitable method found to override [E:\Builds\2\BSIP\R4.2_Member_Portal_Release_Build\Sources\UnitTests\obj\Release\Moles\cbmpc\m.g.csproj]

Moles: compilation : project compilation failed with exit code 1

Moles: compilation : compilation failed, retrying without Code Contracts