Hello. I have a DirecTV HR24-100 DVR and I recently purchased the AM21 Off-Air Tuner to receive off air channels. Before I bought it, I had my antenna hooked up directly to the TV. I was getting 6 channels. All were around 55-60% signal strength. I hooked up the AM21, did the Initial Setup and everything, and now I'm only getting 3 channels. I was getting channel 13-1, 13-2, 13-3, 19-1, 19-2 and 19-3, now I'm only getting 13-1, 13-2 and 13-3. I am not sure why. The channel 19's (WZMQ) are my favorites. Why is this happening?