Surround sound from Sky +

I have set up a Yamaha RXV361 AV receiver with Tannoy EFX speakers and connected the Sky+ with digital optical and DVD with Digital coaxial.

When I play a DVD sound is fine from all speakers.

When I watch sky+ sound only comes from front R & L speakers and sub woofer.

Any suggestions how I rectify this?
i just bought a Yamaha RX V361 and can not get the surround sound to play with TV, it only works with DVD's