Mocking DateTime.Now with 5.3.5

Hi, mocking DateTime.Now doesn't work for me.

Here's the code

class Timer
{
    public void Tick()
    {
        if (DateTime.Now == DateTime.MaxValue)
            throw new Exception("End of time!");
    }
}

[TestFixture]
public class MyTests
{
    [Test, Isolated]
    public void TestTimer()
    {
        Isolate.WhenCalled(() => DateTime.Now).WillReturn(DateTime.MaxValue);

        var timer = new Timer();
        timer.Tick();//should throw
    }
}

And here's the exception:
------------------------------------------
TypeMock.TypeMockException :
*** No method calls found in recording block. Please check:
* Are you trying to fake a field instead of a property?
* Are you are trying to fake mscorlib type?
------------------------------------------

I'm using Typemock 5.3.5