2005 Volvo XC90 all wheel drive

is it possible that somehow the AWD is not working and the vehicle only functions as a front wheel drive ? It is sliding around the snow and can not make is up a small incline......i am not using snows but still does not seem right. When the car was trying to get up my driveway and spinning in the snow, I could only see the front wheels moving...not the rears.

Thanks !