Access a Class function with another

Current stage:

Class 1 - box on right:

package 
{
	import flash.display.*;
	import flash.events.*;

	public class box extends MovieClip
	{
		public function box()
		{
		}

		public function moveBoxTo(boxX:int, boxY:int):void
		{
			this.x = boxX;
			this.y = boxY;
		}

	}

}

Class 2 - box on left:

package 
{
	import flash.display.*;
	import flash.events.*;

	public class button extends MovieClip
	{

		private var buttonState:Boolean;

		public function button()
		{
			buttonState = false;
			this.addEventListener(MouseEvent.CLICK, clicked);
		}

		private function clicked(e:Event):void
		{
			if (buttonState === false)
			{
				//this.parent.boxMC.moveBoxTo(0,0);
				buttonState = true;
			}
			else
			{
				//this.parent.boxMC.moveBoxTo(0,0);
				buttonState = false;
			}
		}
	}
}

Box on left is a button which when pressed moves button on right. Except it doesn’t as I can’t access a class method from within another.

Solution any one?