R – Getting This project doesn’t have any tests error in cc.net

I am getting the following Warnings while running tests using cc.net

c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Microsoft.Common.targets (,): warning MSB3245: Could not resolve this reference. Could not locate the assembly "nunit.framework, Version=2.4.8.0, Culture=neutral, PublicKeyToken=96d09a1eb7f44a77, processorArchitecture=MSIL". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.
C:\srce\TP\ITTests\ITTests\ITTests\Tests.vb (1,): warning BC40056: Namespace or type specified in the Imports 'NUnit.Framework' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases.
C:\srce\TP\ITTests\ITTests\ITTests\kingTests.vb (1,): warning BC40056: Namespace or type specified in the Imports 'NUnit.Framework' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases.

Tests run: 0, Failures: 0, Not run: 0, Time: 0 seconds
No Tests Run
This project doesn't have any tests

Any idea why? as All paths seems to be correct

Kind Regards