I have purchased the Digitech communicator model DC-1003 (2 pack) as a Christmas present. We cannot get them to work! Brand new batteries, can change channels, can scan channels, can adjust volume, can see the tx indicator come on when you hit the PTT button, but they do not receive a signal (no sound and no RX indicator). We have read every line of the instruction manual (twice). Could you please tell me what we are doing wrong? Thanks.