4×4 not workzing

hello fellas, need some help please.
I have an outlander 800XT and the 4×4 is not working.
The 4×4 light turn on only when I accelerate the bike, but it’s not engaging in four-wheel-drive
Even as I’m driving and I accelerate the bike the 4 x 4 light turns on momentarily while I have the bike accelerated and as I release the throttle the light turns off but again the 4 x 4 is not engaging, any suggestions?