Wheels can't touch the ground

Hello, I’m doing the unity’s car tutorial and I found something stange on my car.

alt text

I was followed the steps and when I check the code.

if(w.collider.isGrounded)
		{
			if(w.steerWheel)
				canSteer = true;
			if(w.driveWheel)
				canDrive = true;
		}

It’s never been entry.

Is something I missing to do?

-------------------------------------------7-5-2013
More strange things.

I was check the code which one of the collider.

if(w.collider==MeshCollider)print("yes");else print("NO");
		print(w.collider);

Then show me (Unity Engine.Wheel Collider)

But the conditional statement is show me the reverse answer.

What’s wrong with it?

-------------------------------------------7-5-2013
I try do check is it my model is wrong.

Then I create the simply model to check. Add the collider independently.

But the result is same.

alt text

What’s Wrong!? please HELP!!!

it looks to me like your wheels/tyres do not have colliders on them. In Unity colliders are shown on a model as a green wireframe. Your image above shows this on the body of the car and not the wheels.