Unity 3D UI Button Not Working When Touched (Mobile)?

I have a button on a canvas that is supposed to activate a pull spring on a pinball board for mobile devices as it is held down. Once the button is released, the pull spring is supposed to launch the ball onto the pinball board. The button is name "pullButton" on the hierarchy. However when the button is touched nothing happens. This script is attached to pull spring game object. I have referred to the button in the inspector in Unity.

I have looked into the Unity documentation and answers, but found no such resolution. This script currently works with a keyboard input. Any help would be appreciated!

 #pragma strict
 
 var inputButtonName : String = "Pull";
 var distance : float = 50;
 var speed : float = 1;
 var ball : GameObject;
 var power : float = 2000;
 var Button :GameObject;
 
 private var ready : boolean = false;
 private var fire : boolean = false;
 private var moveCount : float = 0;
 //var buttonTouch = false;
 
 function OnCollisionEnter(_other : Collision) {
 if(_other.gameObject.tag == "Ball"){
     ready = true;
 }
 }
 
 function Update () {
     var down = Input.GetButtonDown("pullButton");
    // var touches : Touch[] = Input.touches;
   //  for (var touch : Touch in Input.touches) {
   //      if(Input.GetButtonDown("Button")){
   //      buttonTouch = true;
   //  }
 
   //  }   
     if(Input.GetButton(inputButtonName) || down){
         //As the button is held down, slowly move the piece
         if(moveCount < distance){
             transform.Translate(0,0,-speed * Time.deltaTime);
             moveCount += speed * Time.deltaTime;
             fire = true;
         }
     }
     else if(moveCount > 0){
         //Shoot the ball
         if(fire && ready){
             ball.transform.TransformDirection(Vector3.forward * 10);
             ball.GetComponent.<Rigidbody>().AddForce(0, 0, moveCount * power);
             fire = false;
             ready = false;
         }
         //Once we have reach![alt text][1]ed the starting position fire off!
         transform.Translate(0,0,20 * Time.deltaTime);
         moveCount -= 20 * Time.deltaTime;
     }
 
     //Just ensure we don't go past the end
     if(moveCount <= 0){
         fire = false;
         moveCount = 0;
     }
 
 }

[1]: /storage/temp/83331-pull.jpg