apple tv only playing 800x600

I just setup a new Apple tv and I can only play it in 800 x 600 60hz. My tv is a Vizio e422va that supports 1080p 60hz. Why can't I set my resolution to 1080? I have a bluray player that I've tested with the same hdmi cable to the same input and it plays 1080p 60hz fine. Any ideas?