From everything I see, it looks like it should be working appropriately. I would go with the idea that the detection app that is not understanding how Virtu works. Since the detection app is merely just saying what is currently in use and not stressing your machine at all, Virtu is doing what it's supposed to and not using the power of your GTX 660 Ti. However, if you run a game, Virtu is supposed to switch to the GTX 660 Ti. A "better" test would be something like
3D Mark 11, which is a common benchmark reviewers run when they test video cards. If you download and run the "Performance" preset which comes with the free edition, it looks like you should get ~9000 points as a final result. If you get that, then ignore what the detection app says, you're set up properly with the 660 Ti.