Just a couple of questions.
First off, are you following spektrum's guide to binding correctly?

Secondly, are they both new? Or did the problem just recently pop up? If at all possible, try binding the receiver to another transmitter or try binding another receiver to this transmitter. It's possible that either the receiver or transmitter is faulty. If 1 of them is faulty, you'll have to contact spektrum and have it fixed.

Good luck!