Some times with the older stuff, I had to hold the bind button for about 3 seconds and then let it up. Now days, once the Txer says "Binding" I let the button up.

Also, Make sure you get a few feet away from the Rxer with Txer. you can "swamp" the Rxer with to much Txer signal. I usually put myself between the two.

But, if you are not seeing a repeated flashing from the LED on the Rxer, the Rxer is not going into bind mode.