How to load two different scenes from a single UI button using PlayerPrefs

The game contains two controls - joystick and Accelerometer which i want to switch in the settings menu.
I have used PlayerPrefs to assign both the buttons in the settings menu, an integer.
For eg. for joystick

PlayerPrefs.SetInt ("Control", 1);

And for accelerometer it is 6 (both the integers are the sceneindex of the scenes).
I basically want, when i click the start button it should take the value of playerprefs and load that scene.
The below code is what i tried but it didnt worked.

 public void LoadByIndex (int i)
    		i = PlayerPrefs.GetInt ("Control");
    		SceneManager.LoadSceneAsync (i);


using UnityEngine.SceneManagement;

    public class SceneController : MonoBehaviour 
         void Start()
              LoadByIndex( PlayerPrefs.GetInt("Control"));
         public void LoadByIndex (int index)
              SceneManager.LoadScene (index);

Have you added all scenes to BUILD SETTINGS → Scenes in build ??