Advice needed!!!

[Superstar]

I bought a 2nd hand receiver for my KO 2.4 for my 2wd. Been running one receiver between two cars for month or so since my last receiver broke.

I have plugged it all in, all the lights are coming on but the it isnt binding together and I have no idea why. What can I do to set the new receiver up to my transmitter?

Transmitter is KO Esprit 3 universe.

Module is KO RF-901S - 2.4 ghz

Receiver is KO KR-408S mini receiver

Very confused any any help will be VERY appreciated