How to call functions?

Hello, I've made a script that tries to access another script to do damage to an enemy and I've hit a bump in the road. I have a script thats attached to my camera which contains a Update function that lets you select an enemy and also it has an else statement. That else statement's supposed to run a function called HitTarget if you press 1. I keep having a error when I run the game. I don't get what i'm doing wrong but its probably a simple mistake. Heres the two scripts that i have.

 //Targeting.js attached to camera
 var target : GameObject; //The target you want to attack
 var EnemyTargetted : boolean = false;
 public var damage = 7;
 
 public var health = 74;
  
 function Update (){
 //find the enemy you want to attack
     var hit : RaycastHit;
     if(Input.GetButtonDown("Fire1")){
         var ray : Ray = gameObject.camera.ScreenPointToRay(Input.mousePosition);
         if(Physics.Raycast(ray, hit)){
             if(hit.collider.tag == "Enemy"){
                 target = hit.collider.gameObject;
                 EnemyTargetted = true;
 
             }       
             else{
             //normal attack by pressing 1
             if(Input.GetKeyDown ("1")) {
             HitTarget ();
             }
             }        
         }
     }
     
     
 }
 
 function HitTarget (damage : int) {
     target.GetComponent(NewBehaviourScript).Hit(damage);
 }

Heres the script that the enemy has (still in progress).

 var damage = 3;
 var InSight : boolean;
 var startingHealth = 75;
 private var enemyHealth : int;
 
 function Start () {
     enemyHealth = startingHealth;
 }
 
 function Hit (damage : int) {
     enemyHealth -= damage;
     if (enemyHealth <= 0) {
         Destroy (gameObject);
     }
 }
 
 function OnTriggerEnter (other : Collider){
     if(other.tag == "Player"){
        InSight = true;
     }
 }
 
 function OnTriggerExit (other: Collider){
     if(other.tag == "Player"){
         InSight = false;
     }
 }
 

I get this error when i try to run the game :The best overload for the method 'Targeting.HitTarget(int)' is not compatible with the argument list '()'.

Please help I can't continue my game without this being fixed.