Ultravox not switching on AV input

[clifton]

Hi ppl

I got an Ultravox 15" television, and when a video and audio input are fed either through the scart plug or else through the phono plugs on the back of the set, the set doesn't work. i.e. it remains as if no input is fed (the usual blue screen). When using the tuner the set works fine.

Can someone pls help me