Dispatch an event from root which should received by childs

1

Hi,

I have a class, which extends flash.display.Sprite.

package {
	import flash.display.Sprite;
	import flash.events.Event;
	
	public class Circ extends Sprite {

		public function Circ() {
			init();
			**this.addEventListener("MainEvent", onMainEvent);**
		}
		public function init():void {
			
			var tmpCol:uint = Math.random()*16000000;
			var tmpX:uint =  Math.random()*400+50;
			var tmpY:uint =  Math.random()*200+50;
			
			this.graphics.lineStyle(1);
			this.graphics.beginFill(tmpCol);
			this.graphics.drawCircle(tmpX, tmpY, 50);
			this.graphics.endFill();
		}
		**public function onMainEvent(e:Event):void {
			trace("MainEvent occurs!");
		}**
	}
}

These elements (Circ) will be added to the main timeline and should be listen
to the Event “MainEvent”.
I will dispatch an event (flash.events.Event) from root which should be
received by every Circ instance (children of root) on the stage.

/**
* first frame timeline
*/
import flash.events.Event;

for (var i:uint = 0; i < 5; i++) {
	this.addChild(new Circ());
}
**this.dispatchEvent(new Event("MainEvent"));
**

I will that every Circ instance make the output “MainEvent occurs!”.

But this doesn’t work.
Could anyone help?