Ontriggerenter button prompt + material change?

Hey, I know this sort of question has been asked countless times before, but I'm still hoping for some help, if anyone can be of service.

In my scene, I have a piece of paper sitting on a desk. When I walk up to it, I want a GUI message to appear, telling me to "Press 'Action'" which I have bound to the E key. Upon pressing the button, the texture on the paper is to change, giving the effect of it having been drawn on. I have 7 different drawings and one blank paper material. Here's my code so far.

     var hasCollided : boolean = false;
     var labelText : String = "";
 public var textureList : Texture[];
 public var objectList : GameObject[];
 public var textureNumber : int;
 var coolDown : int = 1;
 var lastClickTime : float;
 
      
     function OnGUI()
     {
     if (hasCollided ==true)
     {
     GUI.Box(Rect(140,Screen.height-50,Screen.width-300,120),(labelText));
     }
     }
      
     function OnTriggerEnter(c:Collider)
     {
     if(c.gameObject.tag =="Player")
      
     {
      
     hasCollided = true;
     labelText = "Paper - Press 'Action'";
      
     }
 }
 function Update ()
 {
     if (Input.GetButtonDown("Action"))
     {
         if(lastClickTime + coolDown < Time.time)
         {
             lastClickTime = Time.time;
 
             textureNumber ++;
             if (textureNumber > textureList.length - 1)
             {
                 textureNumber = 0;
             }
 
             for (var i = 0; i < objectList.length; i++)
             {    
                 objectList[i].renderer.material.mainTexture = textureList[textureNumber];
             }
         }
     }
 }
      
     function OnTriggerExit( other : Collider ){
     hasCollided = false;
      
     }

My problem is pressing the action button won't do anything, even though it is set up. The button prompt appears/disappears fine, however. Can someone please revise my code?