Rigidbody not working?

I've attached my CarController script to a Car prefab. The car has a Rigidbody added by the "Add component" thanks to the inspector menu.

But it seems I cannot access the value of any attributes of the Rigidbody in my script.

Code (CSharp):

1.  
2.    private Rigidbody m_Rigidbody;
3.    void Start()
4.     {
5.         m_Rigidbody = GetComponent<Rigidbody>();
6.     }
7.  
8.     void Update()
9.     {
10.         if (m_Rigidbody.velocity > 5)
11.         {
12.             //Do stuff
13.         }
14.     }

> NullReferenceException: Object reference not set to an instance of an object

 

Sorry I didn't want to flood the post with 100 lines of code...

Yes it is on line 10.

How come it's null, since my GameObject/prefab has one?

Here is what I have in my GameObject inspector.

If you want the full code, I can upload it if you want.

 

I think the problem is not this. The Rigidbody is good, but it's link to the logic of my game.

I'm using a python client to spawn a Car, so I used a Mains Thread Dispatcher to Instantiate Cars in Threads. And I think o'm not very Thread Safe on what i'm doing.

Thanks anyway