How do I set up a GUITexture as a button? (Java Script)

I added GUITexture by going to Game object>>Create Other>>GUI Texture and added its texture in the inspector what I want now is when the user touches (Game is for android and IOS) that GUITexture to move cube up I tried this code

 var up : GUITexture;
 var player : Rigidbody2D;


 function Update () {
 
 for (var evt : Touch in Input.touches) {

 var HitTest1 = up.HitTest(evt.position);

 if (evt.phase == TouchPhase.Began) {

 if(HitTest1){

 player.rigidbody2D.AddForce(Vector2(-2,0));

 fireButton.enabled = false;

 } 
 } 
 } 
 }

but it didn't work :( what can I do ?

I tried this code blew as well but didn't work can some one tell me why

 var up : GUITexture;


 function Update () {

 if(Input.touchCount > 0){
 var touch: Touch = Input.touches[0];
 if(touch.phase==TouchPhase.Began&&up.HitTest(touch.position)){
 Debug.Log("Touch working");
 }
  }
   }