DF = Dual Conversion FM so it needs a Futaba, dual conversion FM reciever crystal on whatever channel your transmitter is on.

Next, Airtronics is positive shift, Futaba is negative shift so if the radio doesn't allow you to change the shift type it won't work anyways.

Last, mixing and matching crystals w/o knowing what you are doing where a nitro rc helicopter is concerned is taking your life, and that of any spectators in the vacinity in your hands. You were lucky to get the results you did, if had worked on the bench and not in the air you could have had a handful of trouble on your hands.