I have just bought a. I have just bought a Sony DAV-dz260 home theatre system. I connected it viz

Question

I have just bought a Sony DAV-dz260 home theatre system. I connected it viz HDMI to my 1080p tv and it works fine. I also have a Sony PS3 connected via HDMI to my TV and this works fine too. I have connected the PS3 via optical to the DAV-DZ260 but cannot output the sound through the DAV-DZ260. When using the DVD function of the DAV-DZ260, the speakers work fine, just no sound from the PS3 via optical....Any ideas, most welcome