Antenna is not hooked up to television.
Make sure that the antenna cable is correctly connected to the television. If it doesn't work there appears to be no signal.
Problem is caused by television broadcast
Television is in EXT or SIDE mode, and there is no external source provided, so screen mute (black screen) is activated.
If you are using an accessory device (DVD, DVR, or VCR), be sure the device is on and running.