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");
	}
}

If message is false, then please check if it is properly set in OnTriggerEnter (maybe your player object has no Player tag set?). Additionally, you can check if OnTriggerExit is not called.