Sky optical problems (1 Viewer)

Hi, I have a Samsung HT-D4500 surround system, I've had it connected to the tv via HDMI and from the TV to the surround system via an optical cable, it's all been working fine, but recently I decided to connect the Sky box directly to the surround using the optical cable, I've done this a while ago, so I know it works that way, but for some reason no matter how many times I try, I get no sound, yet I'll switch the optical cable back to the tv and I get sound again, I first noticed their was a problem when I was watching a film on Netlix with the PS3 and decided to connect that directly to the surround and noticed there was no sound that was on the ps3 either, anyone have any idea's?

Many STB kill the other outputs when using HDMI.

Is there any way to remedy this, I have tried removing everything except the sky box and the surround system and still nothing