Adding force to a 2d object in specified direction not working?

So I have this boss, it's supposed to punch the player in the direction the boss is facing, like a knockback. This wont work though, I cant figure out why. Any ideas or tips?

Also I know its a very messy script, spent all day

(It's the Knockback function the problem lies I'm pretty sure)

 #pragma strict
 
 var Distance : float;
 var Health = 200;
 var AggroRadius = 5.0;
 var target : Transform;
 var MoveSpeed = 7;
 var AttackRange = 5;
 var Aggroed = false;
 var inAttackRange = false;
 var StartMoving = false;
 var FacingRight = true;
 var xPositionDraugr = 0;
 var anim : Animator;
 var flipside = 0;
 
 
 function Start () 
 {
  
 }
  
 function Update () 
 {
 
 if (GetComponent(Mermaid).xPositionMermaid < xPositionDraugr) 
 flipside = 0;
 else
 flipside = 1;
 
 
 if (flipside > 0 && !FacingRight) 
 Flip();
 else if(flipside < 1 && FacingRight)
 Flip();
 
 xPositionDraugr = transform.position.x;
 
 
 Distance = Vector2.Distance(transform.position, target.transform.position);
 
 if (Distance < AggroRadius) {
 Aggroed = true;
 return;
 }
 
 if (Aggroed == true && StartMoving == true) {
 MoveToTarget();
 
 }
 if (Distance < AttackRange) {
 inAttackRange = true;
 StartMoving = false;
 }
 if (inAttackRange == true) {
 StartMoving = false;
 KnockBack();
 }else {
 
 StartMoving = true;
 }
 
  //find spilleren
  
  
  //gå hen mod ham
  
   
 }
 
 
 function MoveToTarget()
 {
 
 var delta = target.transform.position - transform.position;
           delta.Normalize();
          
           var moveSpeed = MoveSpeed * Time.deltaTime;
      anim.SetInteger("Speed", MoveSpeed);
           transform.position = transform.position + (delta * moveSpeed);
 }
 
 function KnockBack() {
 Debug.Log("knockbcked");
 
 if (FacingRight == true) {
 target.rigidbody2D.AddRelativeForce (-10, 0, 0);
 } else {
 target.rigidbody2D.AddRelativeForce (10, 0, 0);
 }
 //GetComponent(Mermaid).Health-= 23;
 }
 
 function Flip () {
 Debug.Log("flippin");
 FacingRight = !FacingRight;
 
 var theScale : Vector3 = transform.localScale;
 theScale.x *= -1;
 transform.localScale = theScale;
 }