Progress Bar at Game StartUp

Good evening to all, I'm struggling with Unity to create a nice progression bar when the game starts that doesn't need any button to start loading.

I created an Empty Object called LoadingGame whose children are the background Image with its own Canvas and the Slider.

Then I created a new GameObject called LoadScript to which I assigned the following script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using UnityEngine.SceneManagement;
 
 public class LoadingScript : MonoBehaviour {
 
 
     public GameObject LoadingScreenObj;
     public Slider MySlider;
 
     AsyncOperation async;
 
     // Use this for initialization
     void Start () {
         StartCoroutine (LoadMyScreen ());
     }
 
     IEnumerator LoadMyScreen()
     {
         LoadingScreenObj.SetActive (true);
         async = SceneManager.LoadSceneAsync (0);
         async.allowSceneActivation = false;
 
         while (async.isDone == false) 
         {
             MySlider.value = async.progress;
             if (async.progress == 0.9f)
             {
                 MySlider.value = 1f;
                 async.allowSceneActivation = true;
             }
             yield return null;
         }
     }
     // Update is called once per frame
     void Update () {
         
     }
 }

I assigned the slider and the LoadingGame as references to the variables. I also defined the scene order in Build Settings.

The second scene is made by a plane and a "capsule" character free to move.

When I click play, the progress bar is permanently loading and reloading several times in a second.

How can I solve my problem? Here's a picture of my layout: [IMG]http://i68.tinypic.com/51q6bs.png[/IMG]

I would be really thankful to anyone answering me