Actionscript3: Counter Sysytem

I’m creating a shooting gallery, and I have most of it functioning, but the counter which is in it own class named “Board” is the problem. I have a main, ducks and board class. I’m trying to get the counter (board) to count down each time a duck is shot, so it’ll start from 8 ducks; shoot one, and it’ll count down to 7, 6, 5 … etc. The board graphic made in flash is place in the upper right corner. After all of the ducks are gone a sign will pop up saying"You Win"

package
{
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;

[SWF(width="800", height="600", backgroundColor="#E6FCFF")]

public class Main extends Sprite
{
    private var _sittingDucks:Array = []; //always set your arrays with [] at the top
    private var couter:TextField;
    
    
    public function Main()
    {
        //adding the background, and positioning it
        var background:Background = new Background();
        this.addChild(background);
        background.x = 30;
        background.y = 100;
        
        for(var i:uint = 0; i < 5; i++)
        {
            //adding the first cloud, and positioning it
            var clouds:Clouds = new Clouds();
            this.addChild(clouds);
            clouds.x = 130 + Math.random() * 600; //130 to 730
            clouds.y = 230;
            clouds.speedX = Math.random() * 3;
            clouds.width = clouds.height = 200 * Math.random()//randomly changes the clouds demensions
        }    
        
        var waves:Waves = new Waves();
        this.addChild(waves);
        waves.x = 0;
        waves.y = 510;
        waves.speedX = Math.random() * 3;
        
        
        for(var j:uint = 0; j < 8; j++)
        {
            var ducks:Ducks = new Ducks();
            this.addChild(ducks);
            ducks.x = 100 + j * 100;
            ducks.y = 475;
            _sittingDucks.push(ducks);
            ducks.addEventListener(MouseEvent.CLICK, ducksDestroy);
        }
        
        var waves2:Waves = new Waves();
        this.addChild(waves2);
        waves2.x = 0;
        waves2.y = 520;
        waves2.speedX = Math.random() * 3;
        
        var setting:ForeGround = new ForeGround();
        this.addChild(setting);
        setting.x = 0;
        setting.y = 50;
        setting.width = 920;
        
        var board:Board = new Board();
        this.addChild(board);
        board.x = 570;
        board.y = 35;
        
        
    }
    private function ducksDestroy(event:MouseEvent):void
    {
        //store the crow we clicked on in a new array
        var clickedDuck:Ducks = Ducks(event.currentTarget);
        
        //remove it from the crows array
        //find the address of the crow we are removing
        var index:uint = _sittingDucks.indexOf(clickedDuck);
        
        //remove it from the array with splice
        _sittingDucks.splice(index, 1);
        
        //remove it from my document's display list
        this.removeChild(clickedDuck);
        
        trace(_sittingDucks.length)
    }
}

}

package
{
import flash.events.Event;
import flash.events.MouseEvent;

public class Ducks extends DuckBase
{
    public var speedX:Number = 5;
    
    
    public function Ducks()
    {
        super();
        
        this.addEventListener(Event.ENTER_FRAME, moveDucks);
        this.stop();
        this.buttonMode = true;
    }
    
    private function moveDucks(event:Event):void
    {
        var d:DuckBase = DuckBase(event.currentTarget); //so we don't have to use the full event name
        
        this.x += speedX;
        
        if(this.x > 800) //starts from left at 800
        {
            this.x = 0; // drops down and loops once hitting 0
        }
        
    }
}

}

package
{
import flash.events.Event;
import flash.events.MouseEvent;

public class Board extends ScoreDisplayBase
{
    
    private var sittingDucks:Array = [];
    
    public function Board()
    {
        super();
        
    
        
        //this.addEventListener(MouseEvent.CLICK, onClick);
        
    }
    
    //private function onClick(event:MouseEvent):void
    {
        //this.board = sittingDucks.length
    }
    
    
}

}