ActionScript 3.0 :: Communicating Between Linked Classes?

I have been struggling with what seems to be simple concept in ActionScript 3.0 - how to communicate between classes. I have a very simple experiment with two movieclips on the stage. They are named YellowBox and RedBox in my library. I have linked the following code to the YellowBox movieclip: 
 
package{    import flash.display.MovieClip;    import flash.events.MouseEvent;        public class YellowBox extends MovieClip    {                public function YellowBox()        {            this.addEventListener(MouseEvent.ROLL_OVER, rollOverHandler);        }                public function rollOverHandler(event:MouseEvent):void        {            this.x = x + 3;        }    }}
  
What I would like to do is call the YellowBox() function on my RedBox MovieClip with the following code:
 
package{    import flash.display.MovieClip;    import flash.events.MouseEvent;        public class RedBox extends MovieClip    {                public function RedBox()        {            YellowBox();        }    }}
  
I get the following message when I compile: 1136: Incorrect number of arguments.  Expected 1.