Easy explosion script

Here's the script:

 var explosion : GameObject;
 function OnCollisionEnter (collision : Collision) 
 {
     Instantiate (explosion, transform.position, transform.rotation);
     Destroy (gameObject);
 }

But it says that the referenced behaviour is missing. I set the explosion, I gave everything rigidbodies, but it still doesn't work.

[Edit] It looks like Detonator doesn't work.