We need to know exactly which components are involved (which Onkyo/Bravia/Blu Ray models?). Also, which connections are working for you and using which type of cable(?) Drawing us a virtual 'map' of your config that has worked can help ;).
Have an old (probably 8 years old- no HDMI connections and old speaker connections) Onkyo receiver that I had hooked up a home theater system on my old TV. We recently moved and got a 52 inch Bravia 1080p TV. I have hooked up a blue ray DVD player up and have been able to get that to play through the home theater system but can't get the TV to play over it like I did before.
Any one have any ideas?