Most likely, it is a simulcast problem. If you see NFM, the control channel is not being detected. Harris simulcast systems are especially difficult to receive. The only scanners designed to work with simulcast systems are the Uniden SDS100 and SDS200. You can try turning on the attenuator. You can also try moving the scanner around the room and reorienting and adjusting the length of the antenna. You can also try a yagi (directional) antenna. If you are able to receive a much stronger signal from a single tower in the site, you can improve control channel decoding.