I have a new key fob I am trying to program. I have followed the instructions in the manual, but "Push FOB" never flashes on the radio like it's supposed to so it can receive the signal from the fob. It appears then eventually goes off after a minute or so, but never flashes. I have verified that the fob is the correct one and it has a new battery, but I think this is irrelevant since I am not getting the correct prompt for programming from the radio. Any ideas?