MallenP30

I recently bought a futaba 3pmx surface system and it comes with the r603ff, long story short I need more than 3 channels so I bought the r617fs but can't seem to bind them, I wasn't aware they weren't compatible since I did the same thing with my futaba fhss system! Are only cretain air rx's compatible with surface tx's? If so does anybody know of a 6ch rx that is compatible with the 3pmx?