First of all what kind of TX and RX are we talking about? Are you sure that the RX is a match for the TX? Is it the correct shift? Also, are you trying to run a PCM TX on a PPM RX or the other way around? With a little more info we should be able to figure it out really easily. One bit of advice, ALWAYS by a new crystal when you get a new RX to avoid possible bad crystal issues like mentioned before. [8D]