Sprite alpha animation stop working in Unity 4.5?

Hi,
I have a 2d game project which was first built on Unity 4.3.4. I just backed up my project and upgrade unity to 4.5.0 and I found out that all of my game animations that change sprite renderer alpha(fade out animations) stop working. Then I tried unity 4.5.1 and it didn’t work either. When I downgrade unity to 4.3.4 back, all the animations worked properly but it has issue on scene loading (Took so much time to load and crash).
I use this method to track down the alpha value of sprite renderer:

public class Tracker:MonoBehaviour
{
    private SpriteRenderer rend;

	string message = "";

	void Start()
	{
	     rend = (SpriteRenderer)renderer;
	}

	void Update()
	{
	     message = "Alpha = " + rend.color.a;
	}

	void OnGUI()
	{
	     GUILayout.Label(message);
	}
}

However, alpha always = 1(which mean animation not working).

Is there any solution to fix this problem? I appreciate any help and sorry about my English.

Thanks

If anyone meet the same problem like me. You can download the latest unity patch (4.5.1p1) from the link here: http://forum.unity3d.com/threads/unity-patch-releases.246198/

It worked for me!!!