I replaced a tv in my kitchen with a Sylvania TV/DVD/CD/Radio. After following the instructions for setup I get no signal message when trying to plan the TV. The DVD works fine.
Try going into the Menu and find "Scan for channels" or something like that. Push the Select button or some button like that that will allow the TV to scan for channels. Once it completes the scan, you should be able to watch TV normally. Be sure and make certain that either a turned on cable box or an antenna is connected to the Input of the TV.