Are you listening to 155.715MHz WITHOUT a PL Tone enabled? There are 6 towers on that frequencies, each with a different PL Tone. If you're listening to that freq with only one PL Tone you're only going to hear the tower with that specific PL Tone, and that tower is only going to be for one specific area of the county. Listening to that freq WITHOUT any PL Tone enabled will allow you to hear ALL of the towers for the entire county.