MouseDrag() stops working

I have the following piece of code attached to a cylinder, and it works fine, but every time I run it for some time (a matter of seconds), the On MouseDrag() stops working, not detecting my dragging. Any clues?

Code (csharp):

1.  
2. static var strength : float;
3. static var oldMouse: float;
4.  
5.    
6.    function OnMouseDown() {
7.    
8.    oldMouse = Input.mousePosition.y;
9.      
10.    }
11.      
12.    function OnMouseDrag(){
13.          
14.    transform.Rotate( Vector3(strength,0,0) * Time.deltaTime );
15.  
16. }
17. function Update () {
18.    
19.    strength = (Input.mousePosition.y - oldMouse);
20.  
21.  
22.  
23. }
24.  
25.  

Thanks a lot!

 

Does the dragging stop when the mouse moves off the object with the script?

 

I just encountered the same problem. but I've not handled the mouse moving off the obj, I'll try and report here...