Enemy AI won't take Damage

I have a simple combat script set up, but everytime the prefab hits the enemy the enemies health will not go down. I could use any help I'm at the verge of giving up on this I can't figure it out.

 public var path1 : Transform;
 public var path2 : Transform;
 
 public var enemySpeed : int = 6;
 
 public var currentHealth : int = 1;
 public var maxHealth : int  = 1;
 
 private var target : Transform;
 private var controller : CharacterController;
 
 function Start () : void 
 {
     SetTarget(path1);
     controller = GetComponent(CharacterController);
     currentHealth = maxHealth; 
     gameObject.renderer.material.color = Color.red;
 }
 
 function SetTarget(newTarget : Transform) : void
 {
     target = newTarget;
 
 }
 
 function Update () : void
 {
     var lookAtPosition : Vector3 = new Vector3 (target.position.x, this.transform.position.y, target.position.z);
     transform.LookAt(lookAtPosition);
     controller.SimpleMove(transform.forward*enemySpeed);
 
 }
 
 function OnTriggerEnter (node : Collider) : void
 {
     if (node.transform == target)
     {
         if (target == path1)
 
             SetTarget(path2);
                 
         else if (target == path2)
             SetTarget(path1);
 
 }        
 }
 
 function ModifyHealth (change : int) : void 
 {
 {
     currentHealth += change;
     if (currentHealth > maxHealth)
         currentHealth = maxHealth;
     else if (currentHealth <= 0)
             Destroy(this.gameObject);
         
 
 }    
 }
 
 
 
 this is the bullet script
 
 var shot : GameObject;
 function Start()
 {
 }
 
 function OnCollisionEnter(info : Collision) : void {
     if(info.collider.tag == "Enemy"){
         info.collider.SendMessageUpwards("ModifyHealth", -1);
     }
 }
 function Update () {
 if(Input.GetButtonDown("Fire1"))
 {
 var porjectile = Instantiate(shot, transform.position, Quaternion.identity);
 porjectile.rigidbody.AddForce(transform.forward * 1500);
 }
 }