techwood 32832 problem?

I connect my aerial and and the svreen displays a digital reading to say theres no signal, then I connect my video and dvd combi unit using the scart lead to the back of the TV from the unit, press play, then flick through all the non displaying channels, only to find that no image or sound from the video or DVD being played do not appear on amy channel, any ideas, you can email me if you have any ideas, any help warmly and gratefullu appreciated, my email address is markplln2009 at yahoo.co.uk