OnGUI not working?

For some reason, GUI not working when I'm on trigger? Why? This is the script of it. I used this type of script for door, pick up key, and call phone but GUI is not appear!

This script is for key

 var message : boolean = false;
 var LockedTrigger : Collider;
 var UnlockedTrigger : Collider;
 
 function Start()
 {
     LockedTrigger.enabled = true;
     UnlockedTrigger.enabled = false;
     gameObject.SetActive(true);
 }
 
 function OnTriggerStay(other : Collider)
 {
     if(Input.GetButton("e")){
         gameObject.SetActive(false);
         LockedTrigger.enabled = false;
         UnlockedTrigger.enabled = true;
     }
 }
 
 function OnTriggerEnter (other : Collider){
     if (other.gameObject.tag == "Player") {
         message = true;
     }
 }
      
 function OnTriggerExit (other : Collider){
     if (other.gameObject.tag == "Player") {
         message = false;
     }
 }
      
      
 function OnGUI(){
     if(message){
         GUI.Label(new Rect(Screen.width/2 - 75, Screen.height - 100, 300, 30), "Press E to pick up Exit door key");
     }
 }