GetComponent error: Object Reference not set to an instance of an object.

So, I have this big block that is supposed to descend and crush the player when the player steps on a trigger. The console is returning the error
“NullReferenceException: Object reference not set to an instance of an object. bigBlockTrigger.OnTriggerEnter(UnityEngine.Collider other)(at Assets/Scrips/bigBlockTrigger.js:19)”

Here are the two scripts (JAVASCRIPT):

(Code on trigger, “bigBlockTrigger”)

#pragma strict

function Start () {

}

function Update () {

}

function OnTriggerEnter(other : Collider) {
	if(other.tag == "Player")
	{
	print("Woohoo");
	var Moving: bigBlockScript = GetComponent(bigBlockScript);
	Moving.isMoving = true;  
	}
}

And (Code on Block, “bigBlockScript”)

#pragma strict

public var isMoving : boolean = false;
public var speed: int = 2;

function Start () {

}

function Update () {
	if(isMoving == true){
		transform.position -= transform.up * speed * Time.deltaTime;
	}

}

Please help :)!

Try GameObject.findwithtag instead on your first script see if that helps.