[Loading scence] async progress returns always return 0

I everybody, I'm making a loading scence using scene manager LoadScenceAsync. I would use the progress value to have an loading UI, but I have always 0. I found anywhere an answer. Do you know please, how could I do ?

here my code : using UnityEngine; using System.Collections; using UnityEngine.UI; using UnityEngine.SceneManagement;

 public class LevelLoader : MonoBehaviour {
 
     public GameObject LoadingScene;
     public Image LoadingBar;
     public Text textPourcentage; //The text with the percentage increasing
   
     public void LoadLevel (string nomScene) //The name of the scene
     {
         
         StartCoroutine (LevelCoroutine (nomScene));
     }
 
    
     IEnumerator LevelCoroutine (System.String nomScene)
     {
         LoadingScene.SetActive (true);
         
         AsyncOperation async = SceneManager.LoadSceneAsync(nomScene);
  
 
         while (!async.isDone) {
             LoadingBar.fillAmount = async.progress ; //Async progress returns always 0 here      
             Debug.Log(async.progress);
             textPourcentage.text = LoadingBar.fillAmount + "%"; //I have always 0% because he fillAmount is always 0
               yield return null;
 
         }
     }
 }