Wheeled vehicle issues

My vehicle is not moving!!! Please help!!!
This is how i set up my car, joints are parented into root joint instead of connect and how I export my skeletal mesh as FBX:

I import the FBX into unreal as skeletal mesh and change the collision into box and sphere in physical assets.
I also set up the input and blueprints to move the car under vehicle BP.

And I have also set the wheel BP and connect it with the wheel skeleton

[see how it looks like in my game][3]

But it is not moving at all! Can someone find the issue for me please?

common fault check this doc page
https://docs.unrealengine.com/latest/INT/Engine/Physics/Vehicles/VehcileContentCreation/

since your a maya user be careful the root joint MUST be at 0,0,0 the joint axis MUST be aligned to x=forward z=up

place your mesh so that the bottom of the wheels are on the ground