When you do a channel scan, the TV tuner will list only channels it receives from the transmission tower where the antenna is pointed. If you change the pointing direction of the antenna to another transmission tower, it will list the channels of the new direction. Since it can't receive a signal from the previous transmission tower, no channels would be listed from it. Some TV's, like my Samsung, add channels automatically without doing a scan. When ever a prime adds a sub, it is added. My TV tuner is too aggressive and adds 'bounce' signals [from a distant city and not in line] which usually displays as a 'no signal' screen.
If your TV adds channels without doing a scan, you might be able to list and receive signals when you rorate the antenna from two transmission towers
