calling OnGUI events are cancelled by LateUpdate?

hello, I have a camera script that sets camera position.

If I make a button to reset the camera position I press the button to reset the camera and nothing happens.-Why? I tried placing this code after the LateUpdate.

     function  OnGUI(){    
        if (GUI.Button (Rect(780,30,35,20),GUIContent("cam","reset camera position")))
         {
            camera.transform.position = Vector3.one;
         } 
         GUI.Label (Rect(300,300,300,100),GUI.tooltip);        
     }