T8SG and RX2A pro

Hello.
I have been assembling quads for 5 or 6 years, but I have a problem with a setup and I bug ...
I was given a tiny GT8 with a T8SG (v1) and a RX2A pro.
I managed to pair them together.
Under cf, I see the movements of the sleeves and the values are good.
However, I can not move the switches or arm the engines ...
Someone know the secret?
Thanking you in advance
Ps: I'm French, I do not google translate!