Can't Activate/Deactivate Object!

I can’t seem to activate the Death Message in my game when my player dies. I want the message to display for 5 seconds and then disappear, unfortunately I am not getting any error messages so I don’t know what it wrong. Here is my code:

using UnityEngine;
using System.Collections;

public class FallDeath : MonoBehaviour {

	private int scene;
	public GameObject DeathMessage;

	void OnTriggerEnter(Collider other) {
		scene = Application.loadedLevel;
		Debug.Log ("Triggered");

		if (other.gameObject.name == "FPSController") {

			DeathMessage.SetActive(true);
			Debug.Log("Activated");

		
			System.Threading.Thread.Sleep(5000);
	

			DeathMessage.SetActive(false);
			Debug.Log("Deactivated");

			Application.LoadLevel(scene);

		}
	}
}

void OnTriggerEnter(Collider other)
{
scene = Application.loadedLevel;
Debug.Log (“Triggered”);

         if (other.gameObject.name == "FPSController") {
 
             StartCoroutine(Wait());
 
         }
 }

//Add Coroutine

IEnumerator Wait()
{
             DeathMessage.SetActive(true);
             Debug.Log("Activated");
 
         
             yield return new WaitForSeconds(5);
     
 
             DeathMessage.SetActive(false);
             Debug.Log("Deactivated");
 
             Application.LoadLevel(scene);
}

should work try it

System threads take parameters in ms so 5000ms = 5s