What was specifically wrong with the DX8 if it was a setup error with the Aux2 being the gain channel?

Was it a case of not RTMing or was it a technical fault with the DX8

A mate of mine ended up having to have his antenna replaced on his DX8 when he tried to bind one of his BnF aeroplanes. The DX8 failed to do so because you need a pure signal from the transmitter.