Setting Reference in Start() doesn't work

I want to to set the reference in the Start-function to use it later in the script..like this:

public class FallObjectScript : MonoBehaviour {

public GameObject gameController;

void Start()
{
Debug.Log ("Test");
GameObject gameController = GameObject.FindWithTag("GameController");
}

void OnMouseDown()
{
gameController.GetComponent<GameControllerScript>().AddPoints(5);
Destroy (gameObject);
}
}

But it just works like this:

public class FallObjectScript : MonoBehaviour {

public GameObject gameController;

void OnMouseDown()
{
GameObject gameController = GameObject.FindWithTag("GameController");
gameController.GetComponent<GameControllerScript>().AddPoints(5);
Destroy (gameObject);
}
}

If i set the reference in the Start-function it says: "...Object reference not set to an instance of an object...".
Why dosen't it work?

 

change
GameObject gameController = GameObject.FindWithTag("GameController");

to

gameController = GameObject.FindWithTag("GameController");

 

Thank you verry much. Was really simple now, but I am quite new in Unity so didn't notice what went wrong.

 

Well, this is not really related to Unity directly. Basically, if you declare a global variable, but then declare it again inside a method, when you try to assign something to the variable, it only uses it in that method instead of saving the reference to the global variable.