transmission is working but why wont the rear wheels spin? on 2002 BMW X5

when I put the car into gear the rear wheels will not spin

Asked by for the 2002 BMW X5
So how is it being driven, rear wheels off the ground? ..................ANY warning lights?
yea we wheel barrow it lol but really the car is awd the front wheels are normal but rear wheels will not move do you think it be the actuator on it?
......DAMN strong wheelbarrow!! I know it's AWD , that's why I was asking how you can tell there is no power transfer to the rear. Again.... NO warning lights are on , or flash while driving? The way you're phrasing your statement you say the 'rear wheels will not MOVE'? ........IF ...the front wheels are on the ground AND moving .....and the rear wheels are ON THE GROUND..........what are they doing??
basically when the truck shifts into gear you can feel that the car wants to move but the rear diff feels stucks and no engine lights it seems all mechanical
So , the car is NOT drivable at this time? Parking brake malfunction?
I had this same problem, and it was indeed the transmission.