Making a Camera View Popup Using OnGUI

Hello, I'm attempting to have a camera view pop up in screen using a trigger as the catalyst.

I've found some similar questions on here and believe I have my code tailored correctly but... well, obviously I'm here.

using UnityEngine; using System.Collections;

public class PlayerDetection : MonoBehaviour {

 private GameObject player; 
 private LastPlayerSighting lastPlayerSighting;
 private bool enemyCam = false;
 public Texture aTexture;

 void Awake()
 {
     player = GameObject.FindGameObjectWithTag(Tags.player);
     lastPlayerSighting = GameObject.FindGameObjectWithTag(Tags.gameController).GetComponent<LastPlayerSighting>();
 }


 void OnGUI()
 {
     if (enemyCam == true)
     {
         GUI.DrawTexture(new Rect(50, 50, 300, 200), aTexture, ScaleMode.StretchToFill, true, 10.0F);
     }
 }

 void OnTriggerStay(Collider other)
 {
     if(other.gameObject == player)
     {
         Vector3 relPlayerPos = player.transform.position - transform.position;
         RaycastHit hit;
         enemyCam = true;
         Debug.Log("Player Detected");



         if(Physics.Raycast(transform.position, relPlayerPos, out hit))
         {
             if(hit.collider.gameObject == player)
             {
                 lastPlayerSighting.position = player.transform.position;
             }
         }
     }
 }

}

Above is my code; there's some extra stuff relating to guard AI scripts, but what's relevant is the OnGUI function and the trigger.

The GUI.DrawTexture function works on it's own, but I can't get it to pop up OnTriggerStay. I DO get a Debug.Log("Player Detected"), so I know the trigger is registering.

Any help is appreciated.