Simple OnGui does not work

I tried everything to get this working but somehow I can’t…

using UnityEngine;
using System.Collections;

public class GameManager : MonoBehaviour {

public static int playerScore01 = 0;  
public static int playerScore02 = 0;




public static void Score (string wallName) {   
	if(wallName == "_rightWall")
	{
		playerScore01 += 1;
	}

	else 
	{
		playerScore02 += 1;
	}
	Debug.Log ("Player Score 01 is" + playerScore01);
	Debug.Log ("Player Score 02 is" + playerScore02);


}

void OnGui() {

	GUI.Label (new Rect (Screen.width / 2 - 150, 20, 100, 100), "bla");
	GUI.Label (new Rect (Screen.width / 2 + 150, 20, 100, 100), "bla");

 }

}

I think the code is fine, but somehow I can’t see the GUI when testing the game… is there a problem in the code I am to dumb to see?

Please help…

It should be OnGUI() not OnGui()