Collision will not work

Hey guys I've put this collision code onto a bullet prefab in my game however it keeps on giving me the same response.

The error it gives me is Script error: OnCollisionEnter This message parameter has to be of type: Collision The Message will be ignored

In my scene there are objects that can be collided with because they have mesh colliers and I also have a terrain in the scene as well. here is the code.

 var Target : GameObject;
 var ObjectName : String = "Bullet";
 function OnCollisionEnter(collision : Collision){
 if (collision.gameObject.tag == ObjectName){
     ("Collision.gameObject.tag equals " +collision.gameObject.tag);
     Destroy(Target);
     Debug.Log("target hit");
 }
 }

So yeah someone please help because I'm running out of options that should work but don't I am also currently using the latest version of unity as well.