Knockback and directions problem

I have this script attached to an object, if my player encounters that object it will be knocked back. I have six directions on which it will be knocked back. This image will show you the different direction of which my player may get knock back. My problem: X=0,Y=1 and X=0,Y=-1 doesn't work, however every other velocity works. How can I also include the directions of X=0,Y=1 and X=0,Y=-1. Thank you and here is my code:

 public class Knockback : MonoBehaviour {

 public float xForceToAdd;
 public float yForceToAdd;
 // Use this for initialization
 void Start () {
     
 }
 
 // Update is called once per frame
 void Update () {
     
 }
 void OnTriggerEnter2D(Collider2D other)  {
     if (other.gameObject.tag == "Player")
     {
         //Store the vector 2 of the location where the initial hit happened;
         Vector2 initialHitPoint = new Vector2 (other.gameObject.transform.position.x, other.gameObject.transform.position.y);
         float xForce = 0;
         float yForce = 0;
         //Grab our collided with objects rigibody
         Rigidbody2D rigidForForce = other.gameObject.GetComponent<Rigidbody2D>();
         //Determine left right center of X hit
         if (initialHitPoint.x > (this.transform.position.x + (this.transform.localScale.x /3)))
         {
             xForce = 1;
         }
         else if (initialHitPoint.x < (this.transform.position.x - (this.transform.localScale.x /3)))
         {
             xForce = -1;
         }
         else
         {
             xForce = 0;
         }
         if (initialHitPoint.y > (this.transform.position.y + (this.transform.localScale.y /3)))
         {
             yForce = 1;
         }
         else if (initialHitPoint.y < (this.transform.position.y - (this.transform.localScale.y /3)))
         {
             yForce = -1;
         }
         else
         {
             yForce = 0;
         }
         rigidForForce.velocity = new Vector2(xForce * xForceToAdd, yForce * yForceToAdd);
     }
     
 }

}

(http://noobtuts.com/content/unity/2d-pong-game/vector2_directions.png)