[JS - 4.6 - UI issue] my script doesn't allow me to change the items text

so I have a gameobject named _GM and I have a game master script that controls when the player gets a coin and when that happens I want it to go to a GUI but it doesn't I have the Image with the text in it inside the canvas so its

Canvas > ScoreGUI > Text

but it gives me an error and just doesn't allow me to change the text here's the script

 #pragma strict
 
     static var currentScore : int = 0;
     
     var offsetY : float = 40;
     var sizeX : float = 100;
     var sizeY : float = 40;
     var textobject : GameObject;
     
     var musicPrefab : GameObject;
     
     function Start () {
         currentScore = 0;
         
     if (!GameObject.FindGameObjectWithTag("MM")) {
         var mManager = Instantiate (musicPrefab, transform.position, Quaternion.identity);
         mManager.name = musicPrefab.name;
         DontDestroyOnLoad (mManager);
         }
 }        
 
 
 
     function OnGUI ()
 {
     GUI2.text = "Score: " +currentScore;
 }

so if anyone could give me an example for the code on line 26 that'd be very helpful considering i'm a newb :D