Increase enegy before shooting

I want the player can create the sphere when he press the right mouse and when I release, the player shoot. Here is my script:

var BulletBossSuper : GameObject;

function Update () {

Shoot();

}

function Shoot()

{

if (Input.GetMouseButtonDown (1))
 	{
  var clone = Instantiate (BulletBossSuper, transform.position,

Quaternion.identity);

}




if (Input.GetMouseButtonUp (1))

{

clone.rigidbody.AddForce(transform.forward*1000);

//Report at this line : "Object reference not set to an instance of an object"

} 	 	}

How can I make this script work

Regards

I think you want to this…

var BulletBossSuper : Rigidbody;
var clone;

function Update ()
{
    Shoot();
}

function Shoot()
{
    if (Input.GetMouseButtonDown (1))
    {
        clone = Instantiate (BulletBossSuper, transform.position,Quaternion.identity);
        clone.rigidbody.Sleep();	
    }

    if (Input.GetMouseButtonUp (1))
    {
        clone.rigidbody.WakeUp();
	    clone.rigidbody.AddForce(transform.forward*1000);
    }
}