Re: Cable TV
You may have 2 sources of TV signal, antenna and cable. If you are using TV, then your antenna should be up and oriented to the transmitters (unless it is omnidirectional, recieves all directions equally poorly) and the amplifier should be on. Then set the TV to 'TV mode' and have it search for channels.
If you are using cable, make sure you are hooked to an active cable outlet, and that the amplifier for the antenna is OFF. Then set the TV to 'cable' mode and again have it search for channels.