PB VM160T remote control after association

Equipped with a VM160 sequencer and a VM160T 4-channel remote control, the latter causes me some problems.

Indeed there are periods or only, the first channel works and not the other 3 channels (Leds 2 to 4 do not light up when keys are pressed) and periods where everything works normally.

It is not the sequencer VM160DT that loses its programming.

I already had this problem on the first remote control and I had to buy one.
Can you explain to me the cause and specify a solution.