You couldn't have set up the zip codes if the dvr was not recognizing the AM21, because unless the AM21 is connected you do not have any antenna options. I was going to suggest you check all your antenna connections,because unless the AM21 is receiving a signal from the antenna you will not see any of the OTA channels. I just had to go 40 feet back up on the roof because I screwed up a crimp connection, of course it had to be the one on the antenna and not one I could get to from the ground.