2D array initialized but send Null

Hello !

Here's the issue: I got a simple class named Room

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Room : MonoBehaviour {
 
     public int PosX;
     public int PosY;
 //don't mind the next variables
 public bool HasBeenAdded = false;
 public List<Room> listeRoomsLinked = new List<Room>();
 public bool IsEntree = false;
 public bool IsSortie = false;
 public int NUMERO = 99;
 
     public Room(int _x, int _y)
     {
         PosX = _x;
         PosY = _y;
     }

 ...

and a 2nd class Named GenerateFloor

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using UnityEngine.SceneManagement;
 
 public class GenerateFloor : MonoBehaviour {

 int WidthMap;
 int HeightMap;
 Room[,] TableauRooms;

 void Awake()
 {
     GenerateTheFloor ();
     DrawMap ();
 }
 
 public void GenerateTheFloor()
 {
     WidthMap = 4;
     HeightMap = 3;

 //Initialize Array[,]
     TableauRooms = new Room[WidthMap , HeightMap];
     //Fill the table with Room Objects
     for (int i = 0; i < WidthMap ; i++)
         for (int j = 0; j < HeightMap ; j++) {
             TableauRooms[i, j] = new Room (i,j);        
         }

 Room _room = TableauRooms [2, 2];
 
 ...

And now

you can see I get null value

But the array[,] has objects in it

What am I doing wrong ? Thanks for reading