2d platformer, coding coin collectable?

So I want to create a system of coins that the player can collect, and even may need to collect x amount to proceed to next scene. So far I have a coin script and coin GUI of the amount collected. They don't seem to work when I apply it to a cube or 'coin'.

here is the script(s);

 function OnTriggerEnter(hit : Collider){
     if(hit.gameObject.tag == "Game Controller"){
     ScoreSystem.myScore += 1;
     Destroy(gameObject,0.0);
   }
 }

and

 static var myScore = 0;
 var DelayTime = 10;
 function Start(){    
 myScore = 0;
 Invoke("myFunction", DelayTime);
 }
  
 function OnGUI(){   
 GUI.Label(Rect((Screen.width / 2) + 20,10, 200, 30), "Coins: " + myScore);
 }

what am i doing wrong? I'm new to coding and unity.