Can't remove object from stage - actionscript-3

Question

I have a problem. I am trying to make a copter game in Adobe Flash with ActionScript 3.0, but now the game works, but the obstacles can't be removed from stage. The obstacles are still going miles out of the stage. How can I remove the obstacles?? and same problem if you are game over, if you are game over the event end, but the last spawned obstacles you see still and aren't removed. And how can I make the obstacles go faster after a period of time??
There are standing some dutch words in it, such as 'hoeSpelen' that is for instructions text en 'af' is for the gameover text and 'tijd' = time and 'balkje' = obstacles.
I hope you can help me.
package
{
import flash.display.MovieClip;
import flash.events.MouseEvent;
import flash.utils.getTimer;
import flash.events.Event;
public class iCopter extends MovieClip
{
private var copter : Copter = null;
private var gameover : GameOver = null;
private var balkje : Balkje = null;
private var tijd : int
var score = 0;
var highscore = 0;
public function onStartButton(event:MouseEvent)
{
startiCopter()
}
public function iCopter()
{
startButton.addEventListener(MouseEvent.CLICK, onStartButton);
af.visible = false
output.visible = false
hscore.visible = false
}
public function startiCopter()
{
removeChild(startButton);
removeChild(hoeSpelen);
removeChild(af);
score = 0
icopterlogo.visible = false
output.visible = true
hscore.visible = true
copter = new Copter();
copter.x = 100;
copter.y = 200;
addChild(copter);
tijd = getTimer();
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
public function onEnterFrame(event:Event)
{
var now:int = getTimer();
if (now - tijd > 1250)
{
var balkje = new Balkje();
balkje.x = 350;
balkje.y = Math.random() * 150;
addChild (balkje);
tijd = now
score = score + 10;
output.text = "score: "+score;
if (balkje.x <= -10) //don't work.
{ //don't work.
removeChild (balkje); //don't work.
} //don't work.
}
addEventListener(Event.ENTER_FRAME, botsing);
}
function botsing (event:Event)
{
for (var i = 0; i < numChildren; i++)
{
if (getChildAt(i) is Balkje || getChildAt(i) is Vloer)
{
var b = getChildAt(i) as MovieClip;
if (b.hitTestObject(copter))
{
removeChild (copter);
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
var gameover = new GameOver();
addChild(af);
af.visible = true
addChild(hoeSpelen);
addChild(startButton);
if (score > highscore)
{
highscore = score
hscore.text = "highscore: "+highscore;
}
}
}
}
}
}
}
Here are the scripts for the copter and obstacle
copter:
muisKlik = mouseClick
muisDruk = mousePush
muisOmhoog = mouseUp
package
{
import flash.display.MovieClip;
import flash.events.MouseEvent;
import flash.events.Event;
public class Copter extends MovieClip
{
var vy : Number = 0;
var muisKlik : Boolean = false;
public function Copter()
{
vy = 5;
addEventListener(Event.ENTER_FRAME, onEnterFrame);
addEventListener(Event.ADDED_TO_STAGE, init);
}
private function init(event:Event)
{
stage.addEventListener(MouseEvent.MOUSE_DOWN, muisDruk);
stage.addEventListener(MouseEvent.MOUSE_UP, muisOmhoog);
}
public function onEnterFrame(event:Event)
{
if (muisKlik == true)
{
y -= vy;
}
else
{
y += vy;
}
}
public function muisDruk (event:MouseEvent)
{
muisKlik = true
}
public function muisOmhoog (event:MouseEvent)
{
muisKlik = false
}
}
}
obstacle:
package
{
import flash.display.MovieClip;
import flash.events.Event;
public class Balkje extends MovieClip
{
var vx : Number = 1;
public function Balkje()
{
vx = 5;
addEventListener( Event.ENTER_FRAME, onEnterFrame );
}
public function onEnterFrame( event:Event )
{
x -= vx;
}
}
}

Answer 1

Not tested - probably full of errors, and I haven't done AS3 in a while:
When you initialize obstacles, pass in the stage object (not sure if this is the best practice)
package {
import flash.display.MovieClip;
import flash.events.Event;
public class Balkje extends MovieClip
{
var vx : Number = 1;
public function Balkje()
{
vx = 5;
if(!stage){
//if stage isn't populated yet, wait for it
this.addEventListner(Event.ADDED_TO_STAGE,addedToStage);
}else{
init();
}
}
private function addedToStage(e:Event):void {
this.removeEventListener(Event.ADDED_TO_STAGE,addedToStage);
init();
}
protected function init():void {
this.addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
public function onEnterFrame( event:Event )
{
x -= vx;
//check x
if(this.x + this.width <= 0 || this.x >= stage.stageWidth) {
if(this.parent) this.parent.remmoveChild(this);
removeEventListener( Event.ENTER_FRAME, onEnterFrame );
}
}
}
}
Again, not tested (is stage.stageWidth correct to get the stage width?) but you get the idea. Check the x of the object, if it is outside the visible stage remove it from its parent (I just put this.parent because you didn't add the obstacle to the stage).
Also, why do you add event listener to ENTER_FRAME in a function called by ENTER_FRAME?