RayCast to send message to the object it hits?

I have a zombie and its got simple AI on it and I have this gun script that should send a message to it. But it keeps saying "Object reference not set to an instance of an object". anyway here are the scripts.

GUN SCRIPT

 var hit : RaycastHit;
 var AmoInClip = 0;
 var Clips = 2;
 var AmoInClips = 30;
 var AmoLeft = 0;
 var BulletDammage = 100;
 var Bullet : Transform;
 var Spawn : GameObject;
 
 
 function Update()
 {
     var hit : RaycastHit;
     
     if(Input.GetMouseButtonDown(0))
     {
         Fire();
     }
     
     if(Input.GetKeyUp(KeyCode.R))
     {
     
         Reload();
     }
     
     if(AmoInClip <= 0)
     {
         
     }
     
     AmoLeft = AmoInClips * Clips + AmoInClip;
     
 }
 
 
 
 function Fire()
 {
     if(hit.gameObject.WithTag("zombie"))
     {
     
     hit.collider.SendMessageUpwards ("ApplyDammage", BulletDammage, SendMessageOptions.DontRequireReceiver);
     }
 }
 
 
 
 
 
 function Reload()
 {
     yield WaitForSeconds(2);
     AmoInClip = 0;
     Clips -= 1;
     AmoInClip = AmoInClips;
     
 }
 
 function OnGUI()
 {
     GUI.Label (Rect (0,80,80,20), AmoLeft.ToString(), "box");
 }

ZOMBIE SCRIPT

 var Distance;
 var Target : Transform;
 var lookAtDistance = 25.0;
 var chaseRange = 15.0;
 var attackRange = 1.5;
 var moveSpeed = 5.0;
 var Damping = 6.0;
 var attackRepeatTime = 1;
 var trigger : boolean = false;
 var TheDammage = 40;
 
 var DamageToMe = 0;
 
 private var attackTime : float;
 
 var controller : CharacterController;
 var gravity : float = 20.0;
 private var MoveDirection : Vector3 = Vector3.zero;
 
 function Start ()
 {
     DamageToMe += Random.Range(1,600);
     moveSpeed = Random.Range(2,5);
     Target = GameObject.FindWithTag("Player").transform;
     attackTime = Time.time;
 }
 
 function Update ()
 {
     Distance = Vector3.Distance(Target.position, transform.position);
     
     if (Distance < lookAtDistance)
     {
         lookAt();
     }
     
     
     
     if (Distance < attackRange)
     {
         attack();
     }
     else if (Distance < chaseRange)
     {
         chase ();
     }
 }
 
 function lookAt ()
 {
     
     var rotation = Quaternion.LookRotation(Target.position - transform.position);
     //transform.rotation = Quaternion.Slerp(transform.rotation, rotation, Time.deltaTime * Damping);
      var dir = Target.position - transform.position;
      dir.y = 0; // kill height differences
      transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(dir), moveSpeed * Time.deltaTime);
 
     
 }
 
 function chase ()
 {
     
     if(trigger == true)
     {
         transform.localPosition.y += 0.05;
     }
     
     
     moveDirection = transform.forward;
     moveDirection *= moveSpeed;
     
     
     moveDirection.y -= gravity * Time.deltaTime;
     controller.Move(moveDirection * Time.deltaTime);
     
 }
 
 function attack ()
 {
     if (Time.time > attackTime)
     {
         
         Target.SendMessage("hurt");
         attackTime = Time.time + attackRepeatTime;
     }
 }
 
 function ApplyDammage ()
 {
     chaseRange += 30;
     moveSpeed += 2;
     lookAtDistance += 40;
 }
 
 function OnTriggerEnter()
 {
     
     trigger = true;
     yield WaitForSeconds(1);
     trigger = false;
 }
 
 function Hurt()
 {
     DamageToMe += 100;
     if(DamageToMe <= 0)
     {
         Destroy(gameObject);
     }
 }