DontDestroyOnLoad not working in Unity 4.3

I just upgraded Unity3D from 4.1 to 4.3. I have a working project, and it doesnt work after the upgrade. The reason is a gameobject seems to be destroyed after I change the scene. Here is some codes:

 public class GameDataObject:Object {
     public string name;
 }
 
 public class GameMainScript:MonoBehaviour {
     public static GameMainScript mainScript;
     public GameDataObject gameDataObject;
 
     void Start() {
         gameSataObject = new GameDataObject();
         gameDataObject.name = "ABC";
         DontDestroyOnLoad(gameDataObject);
         Application.LoadLevel("NewScene");
     }
 }

In NewScene, I have a script:

 Debug.Log(GameMainScript.mainScript.gameDataObject.name);

It shows "ABC" in Unity 4.1, but now in Unity 4.3, it shows "".

Any idea? Thanks