Button inside a window not responding!

I have a button inside a window. The button is showing, it is not responding to clicks! Here is the code:

 void OnGUI()
     {
         useGUILayout = true;
              GUI.skin = mainSkin;    
              if (showWindow)  GUI.DragWindow (2, new Rect (Screen.width / 2 - windowWidth / 2, Screen.height / 2 - windowHeight / 2, windowWidth, windowHeight), Yoyo, "NOTICE");
     } // end of OnGUI      
     void Yoyo(int winID)
     {
             GUI.BringWindowToFront(winID); 
         GUI.FocusWindow(winID);
         if (GUI.Button (new Rect (windowWidth / 2 - buttonWidth / 2, windowHeight - buttonHeight + 50, buttonWidth, buttonHeight), "OKAYss")) 
         {
                     // doesn't work :(
             showWindow = false;
             print ("got a click");
         } // end of if
         GUI.UnfocusWindow();
     } // end of Yoyo