Wharfedale LCD37F1080P and external surround sound

Question

Have connected the Audio cables to the Audio Out connections on the TV and the Audio In on the surround sound system, but cannot get any sound from the TV through the sound system. If I connect the sound system to the DVD player the same way I get sound but only for what is playing on the DVD, and the same happens with the video.

Any ideas how to get the TV to output sound?