[Javascript] My script won't work..

I am trying to create a really simple AI for my zombie. It has no errors in console, however the bullets don't affect the health/zombies.

 var LookAtTarget : Transform;
 var damp : float = 6.0;
 
 var zombieHealth : int = 100;
 var minZombieHealth : int = 0;
 var maxZombieHealth : int = 100;
 var pistolDamage : int = 28;
 
 function Update () {
     ILookAtTarget();
     Health();
 }
 
 function Health(){
     if(zombieHealth < minZombieHealth){
         Destroy(this.gameObject);
     }    
 }
 
 function OnCollisionEnter(collision:Collision){
     if(collision.gameObject.tag.Equals("pistolBullet")){
         zombieHealth -= pistolDamage;
     }
 }
 
 function ILookAtTarget(){
      if(LookAtTarget)
              {
               var rotate = Quaternion.LookRotation(LookAtTarget.position - transform.position); 
               transform.rotation = Quaternion.Slerp(transform.rotation, rotate, Time.deltaTime * damp);
               transform.position = Vector3.MoveTowards(transform.position, LookAtTarget.transform.position, .08);
          }
 }