Itween path problem

Hi guys,

I'm using this code to move a camera around a virtual set:

 switch(SceneManager.instance.scene)
         {
             case 0:
             transform.position = new Vector3 (130f,1f,0);
             break;
             case 1:
             Debug.Log("moving to 1");
             iTween.MoveTo(this.gameObject, iTween.Hash("path",iTweenPath.GetPath("Scene1"),"time",5));
             break;
             case 2:
             break;
             case 3:
             break;
             case 4:
             break;
             case 5:
             break;
             case 6:
             break;
             case 7:
             break;
             case 8:
             break;
         }

But it doesn't work. If I put the code in start function, it works very well but not in update. I'm using Itween visual editor. Any guess?