That would have been a version conflict only ... .Version one and V2 cannot be interchanged .... but Turnigy and Flysky and Eurgle etc .. can all be swapped out .... Identical TX and RX except for labelling.
The 9x can even bind with the HK-TRA-6a -V2 Rx ..... I have used them heaps ..... just again not version 1 or 2 interchangable.