Bug Input.GetAxis("Mouse X") not work on playing but work after building

Code (CSharp):

1.         if (Input.GetMouseButton(1)){
2.            
3.             Debug.Log("Right Mouse Button");
4.            
5.             this.transform.Rotate(new Vector3(0f,-Input.GetAxis("Mouse X"),0f).normalized
6.                                            *rotateSpeed,Space.Self);
7.             Debug.Log(Input.GetAxis("Mouse X"));
8.  
9.         }

When I click play, Debug will show like the below

Code (CSharp):

1.   Debug.Log("Right Mouse Button");  //give me the infomation. But
2.   Debug.Log(Input.GetAxis("Mouse X"));   //always give me 0

But when I build the game, and run, it worked, object rotate well.

 

Is this in the newest build or in the initial one? See http://forum.unity3d.com/threads/mouse-axis-not-working.350344/

 

I try the build 0903, cool, it fixed.