vs 2012: Shims compile

I am trying to make a shim in VS 2012 ultimate as it described in MSDN site:

[TestClass]
public class TestClass1
{ 
    [TestMethod]
    public void TestCurrentYear()
    {
        int fixedYear = 2000;

        using (ShimsContext.Create())
        {
          // Arrange:
          // Detour DateTime.Now to return a fixed date:
          System.Fakes.ShimDateTime.NowGet = 
              () =>
              { return new DateTime(fixedYear, 1, 1); };

          // Instantiate the component under test:
          var componentUnderTest = new MyComponent();

          // Act:
          int year = componentUnderTest.GetTheCurrentYear();

          // Assert: 
          // This will always be true if the component is working:
          Assert.AreEqual(fixedYear, year);
        }
    }
}

see http://msdn.microsoft.com/en-us/library/hh549176.aspx

But when I compile my test project I get a notion in Output:

warning : Some fakes could not be generated. For complete details, set Diagnostic attribute of the Fakes element in this file to 'true' and rebuild the project.

How can I resolve this warning?