Cannot activate stabilisation on Lemon RX receiver from Spectrum DX6i TX

Really need some help here!
I have recently purchased a Lemon RX 7CH receiver for a model plane and have found that I have been unable to remotely activate stabilisation on the receiver via the ‘Gear’ switch on the Spectrum DX6i.
Any ideas anyone - such as online instructions that covers this aspect or a YouTube video?

I can only assume I either have a dud receiver or the DX6i cannot perform this activation!.

go to MissionPlanner:
Initial Setup
Mandatory Hardware
Flight Modes

check the behaviour (your gear switch should be using channel 5 on your dx6i)
and choose the flight mode you want to assign…