WorldToScreenPoint returns the same value when facing the opposite direction.

I have a GUITexture I am placing over the top of an objective to show its position but the problem is it also shows

the when facing the opposite direction. I have found that the WorldToScreenPoint function is returning the same

value when facing the opposite direction, am I doing something wrong or is there a way to fix this? Thanks in

advance c:

         #pragma strict
         
         public var map : GameObject;
         var mainCamera: Camera;
         var mapScreenPos : Vector3;
         var GUIObject : GUITexture;
         
         function Start() {
             //mainCamera = GetComponent.<Camera>();
         }
         function Update() {
             mapScreenPos = mainCamera.WorldToScreenPoint(map.transform.position);
             GUIObject.pixelInset.x = mapScreenPos.x - (Screen.width / 2) -25;
             GUIObject.pixelInset.y = mapScreenPos.y - Screen.height / 2;
             Debug.Log("target is " + mapScreenPos.x + " pixels from the left");
         }