Error #1006: removeChild is not a function - actionscript-3

Question

So I'm trying to create a game where in there's an object falling from the middle and you have to drag it in the left if it's good or right if it's bad.
What I'm having problems with right now is I don't know how the program would know if the object is good or bad. I think.
I'm getting an error:
Error #1006: removeChild is not a function.
I'm newbie at flash, if you have tips or whatever, please share!
http://pastebin.com/AnpN6tEy
import flash.events.Event;
var tray:Array = new Array(Legal2_1,Legal2_2,Legal2_3,Legal2_4,Legal2_5,Legal2_6,Legal2_7,Legal2_8,Legal2_9,Legal2_10,Legal2_11,Legal2_12,Legal2_13,Legal2_14,Legal2_15,Illegal2_1,Illegal2_2,Illegal2_3,Illegal2_4,Illegal2_5,Illegal2_6,Illegal2_7,Illegal2_8,Illegal2_9,Illegal2_10,Illegal2_11,Illegal2_12,Illegal2_13,Illegal2_14,Illegal2_15);
var traypos:int;
var goodpos:int;
var badpos:int;
traypos = (stage.stageWidth / 2)-100;
goodpos = ((stage.stageWidth / 3) -100);
badpos = (((stage.stageWidth/3) *2) -100);
var timerT:Timer = new Timer(1000,120);
timerT.addEventListener(TimerEvent.TIMER, traytimerhandler);
timerT.start();
var secondsT:Number = 1;
function traytimerhandler(event:TimerEvent)
{
//trace("Seconds elapsed: " + seconds);
SpawnTray(null);
secondsT++;
}
function SpawnTray(event:Event):void
{
var trayspawn:int;
trayspawn = int(Math.random() * tray.length);
var trayn:MovieClip = new tray[trayspawn]();
addChild(trayn);
trayn.x = traypos;
trayn.y = -20;
trayn.addEventListener(Event.ENTER_FRAME, MoveTray(trayspawn));
trayn.addEventListener(MouseEvent.MOUSE_DOWN, startDragging);
//trayn.addEventListener(MouseEvent.CLICK, CheckTray(trayspawn));
}
function MoveTray(trayc:int):Function
{
return function(event:Event):void {
var trayn:DisplayObject = event.target as DisplayObject;
trayn.y += 5;
if (trayn.y >= stage.stageHeight + 50)
{
CheckTray(trayc);
trayn.removeEventListener(Event.ENTER_FRAME, MoveTray);
this.removeChild(trayn);
}
}
}
function startDragging(e:MouseEvent):void
{
e.target.removeEventListener(MouseEvent.MOUSE_DOWN, startDragging);
e.target.removeEventListener(Event.ENTER_FRAME, MoveTray);
// surprise! This object will not be moved via MOUSE_DOWN,;
// because it's already being moved
// e.target.addEventListener(
e.target.addEventListener(MouseEvent.MOUSE_UP, stopDragging);
e.target.startDrag();
}
// drag;
function stopDragging(e:MouseEvent):void
{
e.target.stopDrag();
e.target.addEventListener( Event.ENTER_FRAME, MoveTray);
e.target.addEventListener(MouseEvent.MOUSE_DOWN, startDragging);
e.target.removeEventListener(MouseEvent.MOUSE_UP,stopDragging);
return;// emergency exit. We don't need to do more
}
function CheckTray(trayspawn:int):Function
{
return function(event:Event):void {
var trayn:DisplayObject = event.target as DisplayObject;
if (trayn.x <= goodpos)
{
//good side
if (trayspawn<=14)
{
score += 15;
}
else
{
score -= 15;
}
}
if (trayn.x >= badpos)
{
//bad side
if (trayspawn<=14)
{
score -= 15;
}
else
{
score += 15;
}
}
if (trayn.x > goodpos && trayn.x < badpos)
{
//middle
score -= 15;
}
}
}

Answer 1

Implicit coercion error on line 37 is caused by the fact that addEventListener expects function. Change the line to:
trayn.addEventListener(Event.ENTER_FRAME, MoveTray);
"Undefined property event" problems have common cause. Event argument is missing in the signatures of the functions. They should be like this:
function MoveTray(event:Event):void
function CheckTray(event:Event):void

Answer 2

you can access the object that is dispatching the Event with the property target of the Event.
ex:
var m1:MovieClip = new MovieClip();
m1.name = 'm1';
m1.addEventListener( Event.ENTER_FRAME, onEnterFrame );
var m2:MovieClip = new MovieClip();
m2.name = 'm2';
m2.addEventListener( Event.ENTER_FRAME, onEnterFrame );
function onEnterFrame(e:Event):void
{
trace( 'onEnterFrame', e.target.name ); // you could see m1 and m2
}
Hope this could help you