Error #2025: The supplied DisplayObject must be a child of the caller.

Question

Hi All,
I would very much appreciate any help with this.
I am working on a flash piece that will play 4 videos, depending on the button pressed. First button will launch first video, 2nd - 2nd video and so on. Once the Video is done playing, close_btn, learn_more_btn and replay_btn appear, in addition to an ending image that is different for each of the videos( BoxLivePic, BoxSleepPic and BoxFeelPic). So - actually 4 things appear once the movie stops playing and the last image depends on which buttons was clicked...
My issue is, when I click the close button( andI'm sure same will apply for the other 2 buttons), I get the error below:
ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller.
    at flash.display::DisplayObjectContainer/removeChild()
    at AER1_r5_fla::MainTimeline/closeVideo()
I understand is that it's because each Picture is not actually added to the display list, unless the proper button was clicked.. however, I don't know how to fix that! I hope this makes some sence - Below is all of my Code... Thanks a bunch in advance:
import com.greensock.*;
import com.greensock.easing.*;
import com.greensock.easing.CustomEase;
import com.greensock.loading.VideoLoader;
import flash.display.Sprite;
import com.greensock.events.LoaderEvent;
import flash.display.MovieClip;
import flash.display.SimpleButton;
import flash.events.MouseEvent;
//Last Buttons Variables
var close_btn:Button_close = new Button_close();
var learn_more_btn:Button_learn_more = new Button_learn_more();
var replay_btn:Button_replay = new Button_replay();
//Last Pic Variables
var BoxLivePic:Box_Live_Pic = new Box_Live_Pic();
var BoxFeelPic:Box_Feel_Pic = new Box_Feel_Pic();
var BoxSleepPic:Box_Sleep_Pic = new Box_Sleep_Pic();
// Video Variables
var Video_Breathe:VideoLoader = new VideoLoader("Breathe_Video.f4v",{container:this,
                                            x:0, y:0});
var Video_Live:VideoLoader = new VideoLoader("Live_Video.f4v",{conainer:this,
                                             x:0, y:0});
var Video_Sleep:VideoLoader = new VideoLoader("Sleep_Video.f4v",{conainer:this,
                                             x:0, y:0});
var Video_Feel:VideoLoader = new VideoLoader("Feel_Video.f4v",{conainer:this,
                                             x:0, y:0});
// Video complete Event Listeners
Video_Breathe.addEventListener(VideoLoader.VIDEO_COMPLETE, donePlaying_breathe);
Video_Live.addEventListener(VideoLoader.VIDEO_COMPLETE, donePlaying_live);
Video_Sleep.addEventListener(VideoLoader.VIDEO_COMPLETE, donePlaying_sleep);
Video_Feel.addEventListener(VideoLoader.VIDEO_COMPLETE, donePlaying_feel);
OverwriteManager.init(OverwriteManager.AUTO);
//Buttons Invisible
breathe_mc.learn_btn.visible = false;
breathe_mc.video_btn.visible = false;
live_mc.learn_btn.visible = false;
live_mc.video_btn.visible = false;
sleep_mc.learn_btn.visible = false;
sleep_mc.video_btn.visible = false;
feel_mc.learn_btn.visible = false;
feel_mc.video_btn.visible = false;
//Custom Eases
CustomEase.create("myCustomEase", [{s:0,cp:1.14999,e:1.4},{s:1.4,cp:1.65,e:1}]);
CustomEase.create("myCustomEase2",[{s:0,cp:0.97,e:1.22},{s:1.22,cp:1.47,e:1}]);
var timeline:TimelineLite = new TimelineLite({onComplete:showBreathe});
addChild(removeChild(better_mc));
TweenLite.to(better_mc,2,{alpha:1, y:186.6,ease:Bounce.easeOut});
timeline.appendMultiple([
    TweenLite.to(breathe_mc, 1, {alpha:1,y:117,ease:CustomEase.byName("myCustomEase2")}),
    TweenLite.to(live_mc, 1, {alpha:1,y:117, y:37, ease:CustomEase.byName("myCustomEase2")}),
    TweenLite.to(sleep_mc, 1, {alpha:1,y:77, ease:CustomEase.byName("myCustomEase2")}),
    TweenLite.to(feel_mc, 1, {alpha:1,y:77, ease:CustomEase.byName("myCustomEase2")})],1,TweenAlign.START, .2);
function showBreathe():void
    breathe_mc.learn_btn.visible = true;
    breathe_mc.video_btn.visible = true;
    TweenLite.to(breathe_mc.learn_btn, .5, {alpha:1});
    TweenLite.to(breathe_mc.video_btn, .5, {alpha:1});
    TweenLite.to(breathe_mc, 1, {y:77, ease:CustomEase.byName("myCustomEase")});
    //Show Text
    TweenLite.to(breathe_txt_mc, 1,{alpha:1});
//Event Listeners
breathe_mc.addEventListener(MouseEvent.MOUSE_OVER, breatheOpen);
live_mc.addEventListener(MouseEvent.MOUSE_OVER, liveOpen);
sleep_mc.addEventListener(MouseEvent.MOUSE_OVER, sleepOpen);
feel_mc.addEventListener(MouseEvent.MOUSE_OVER, feelOpen);
//Event Listeners for Playing Video
breathe_mc.video_btn.addEventListener(MouseEvent.MOUSE_DOWN, breathe_play_video);
live_mc.video_btn.addEventListener(MouseEvent.MOUSE_DOWN, live_play_video);
sleep_mc.video_btn.addEventListener(MouseEvent.MOUSE_DOWN, sleep_play_video);
feel_mc.video_btn.addEventListener(MouseEvent.MOUSE_DOWN, feel_play_video);
// Event Listener for Close Video
close_btn.addEventListener(MouseEvent.MOUSE_DOWN, closeVideo);
//Functions for VIDEO and LEARN MORE buttons
    function breathe_play_video(event:MouseEvent):void {
    Video_Breathe.load();
    this.addChild(Video_Breathe.content);
    function live_play_video(event:MouseEvent):void {
        Video_Live.load();
        this.addChild(Video_Live.content);
    function sleep_play_video(event:MouseEvent):void {
        Video_Sleep.load();
        this.addChild(Video_Sleep.content);
    function feel_play_video(event:MouseEvent):void {
        Video_Feel.load();
        this.addChild(Video_Feel.content);
function closeVideo(event:MouseEvent):void {
    Video_Breathe.unload();
    Video_Sleep.unload();
    Video_Feel.unload();
    Video_Live.unload();
    removeChild(close_btn);
    removeChild(learn_more_btn);
    removeChild(replay_btn);
    removeChild(BoxLivePic);
    removeChild(BoxSleepPic);
    //removeChild(BoxFeelPic);
// Last Breathe Buttons Added to Stage
function donePlaying_breathe(e:Event):void {
    addChild(close_btn);
    addChild(learn_more_btn);
    addChild(replay_btn)
    close_btn.x = 313;
    close_btn.y = 183;
    learn_more_btn.x = 434;
    learn_more_btn.y = 183;
    replay_btn.x = 554;
    replay_btn.y = 183;
// Last Live Buttons
function donePlaying_live(e:Event):void {
    addChild(BoxLivePic);
    addChild(close_btn);
    addChild(learn_more_btn);
    addChild(replay_btn)
    close_btn.x = 43;
    close_btn.y = 183;
    learn_more_btn.x = 164;
    learn_more_btn.y = 183;
    replay_btn.x = 284;
    replay_btn.y = 183;
// Last Sleep Buttons
function donePlaying_sleep(e:Event):void {
    addChild(BoxSleepPic);
    addChild(close_btn);
    addChild(learn_more_btn);
    addChild(replay_btn)
    close_btn.x = 313;
    close_btn.y = 183;
    learn_more_btn.x = 434;
    learn_more_btn.y = 183;
    replay_btn.x = 554;
    replay_btn.y = 183;
//Last Feel Buttons
function donePlaying_feel(e:Event):void {
    addChild(BoxFeelPic);
    addChild(close_btn);
    addChild(learn_more_btn);
    addChild(replay_btn)
    close_btn.x = 313;
    close_btn.y = 183;
    learn_more_btn.x = 434;
    learn_more_btn.y = 183;
    replay_btn.x = 554;
    replay_btn.y = 183;
// Functions Breathe
function breatheOpen(event:MouseEvent):void
    TweenLite.to(breathe_mc, 1, {y:77, ease:Elastic.easeOut});
    TweenLite.to(breathe_mc.learn_btn, .5, {alpha:1});
    TweenLite.to(breathe_mc.video_btn, .5, {alpha:1});
    //Close Live
    TweenLite.to(live_mc, 1, {y:117, ease:Elastic.easeOut});
    TweenLite.to(live_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(live_mc.video_btn, .5, {alpha:0});
    //Close Sleep
    TweenLite.to(sleep_mc, 1, {y:77, ease:Elastic.easeOut});
    TweenLite.to(sleep_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(sleep_mc.video_btn, .5, {alpha:0});
    //Close Feel
    TweenLite.to(feel_mc, 1, {y:77, ease:Elastic.easeOut});
    TweenLite.to(feel_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(feel_mc.video_btn, .5, {alpha:0});
    //Show Pic
    TweenLite.to(pic_breathe_mc, .5, {alpha:1});
    //Hide Other Pics
    TweenLite.to(pic_live_mc, .5, {alpha:0});
    TweenLite.to(pic_sleep_mc, .5, {alpha:0});
    TweenLite.to(pic_feel_mc, .5, {alpha:0});
    //Show Text
    TweenLite.to(breathe_txt_mc, 1,{alpha:1});
    //Hide Other Text
    TweenLite.to(live_txt_mc, 1,{alpha:0});
    TweenLite.to(sleep_txt_mc, 1,{alpha:0});
    TweenLite.to(feel_txt_mc, 1,{alpha:0});
// Functions live
function liveOpen(event:MouseEvent):void
    TweenLite.to(live_mc, 1, {y:77, ease:Elastic.easeOut});
    live_mc.learn_btn.visible = true;
    live_mc.video_btn.visible = true;
    TweenLite.to(live_mc.learn_btn, .5, {alpha:1});
    TweenLite.to(live_mc.video_btn, .5, {alpha:1});
    //Close Breathe
    TweenLite.to(breathe_mc, 1, {y:117, ease:Elastic.easeOut});
    TweenLite.to(breathe_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(breathe_mc.video_btn, .5, {alpha:0});
    //Close Sleep
    TweenLite.to(sleep_mc, 1, {y:77, ease:Elastic.easeOut});
    TweenLite.to(sleep_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(sleep_mc.video_btn, .5, {alpha:0});
    //Close Feel
    TweenLite.to(feel_mc, 1, {y:77, ease:Elastic.easeOut});
    TweenLite.to(feel_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(feel_mc.video_btn, .5, {alpha:0});
    //Show Pic
    TweenLite.to(pic_live_mc, .5, {alpha:1});
    //Hide Other Pics
    TweenLite.to(pic_sleep_mc, .5, {alpha:0});
    TweenLite.to(pic_feel_mc, .5, {alpha:0});
    //Show Text
    TweenLite.to(live_txt_mc, 1,{alpha:1});
    //Hide Other Text
    TweenLite.to(breathe_txt_mc, 1,{alpha:0});
    TweenLite.to(sleep_txt_mc, 1,{alpha:0});
    TweenLite.to(feel_txt_mc, 1,{alpha:0});
// Functions sleep
function sleepOpen(event:MouseEvent):void
    TweenLite.to(sleep_mc, 1, {y:37, ease:Elastic.easeOut});
    sleep_mc.learn_btn.visible = true;
    sleep_mc.video_btn.visible = true;
    TweenLite.to(sleep_mc.learn_btn, .5, {alpha:1});
    TweenLite.to(sleep_mc.video_btn, .5, {alpha:1});
    //Close Breathe
    TweenLite.to(breathe_mc, 1, {y:117, ease:Elastic.easeOut});
    TweenLite.to(breathe_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(breathe_mc.video_btn, .5, {alpha:0});
    //Close Live
    TweenLite.to(live_mc, 1, {y:117, ease:Elastic.easeOut});
    TweenLite.to(live_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(live_mc.video_btn, .5, {alpha:0});
    //Close Feel
    TweenLite.to(feel_mc, 1, {y:77, ease:Elastic.easeOut});
    TweenLite.to(feel_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(feel_mc.video_btn, .5, {alpha:0});
    //Show Pic
    TweenLite.to(pic_sleep_mc, .5, {alpha:1});
    //Hide Other Pics
    TweenLite.to(pic_feel_mc, .5, {alpha:0});
    //Show Text
    TweenLite.to(sleep_txt_mc, 1,{alpha:1});
    //Hide Other Text
    TweenLite.to(live_txt_mc, 1,{alpha:0});
    TweenLite.to(breathe_txt_mc, 1,{alpha:0});
    TweenLite.to(feel_txt_mc, 1,{alpha:0});
// Functions feel
function feelOpen(event:MouseEvent):void
    TweenLite.to(feel_mc, 1, {y:37, ease:Elastic.easeOut});
    feel_mc.learn_btn.visible = true;
    feel_mc.video_btn.visible = true;
    TweenLite.to(feel_mc.learn_btn, .5, {alpha:1});
    TweenLite.to(feel_mc.video_btn, .5, {alpha:1});
    //Close Breathe
    TweenLite.to(breathe_mc, 1, {y:117, ease:Elastic.easeOut});
    TweenLite.to(breathe_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(breathe_mc.video_btn, .5, {alpha:0});
    //Close Live
    TweenLite.to(live_mc, 1, {y:117, ease:Elastic.easeOut});
    TweenLite.to(live_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(live_mc.video_btn, .5, {alpha:0});
    //Close Sleep
    TweenLite.to(sleep_mc, 1, {y:77, ease:Elastic.easeOut});
    TweenLite.to(sleep_mc.learn_btn, .5, {alpha:0});
    TweenLite.to(sleep_mc.video_btn, .5, {alpha:0});
    //Show Pic
    TweenLite.to(pic_feel_mc, .5, {alpha:1});
    //Show Text
    TweenLite.to(feel_txt_mc, 1,{alpha:1});
    //Hide Other Text
    TweenLite.to(live_txt_mc, 1,{alpha:0});
    TweenLite.to(sleep_txt_mc, 1,{alpha:0});
    TweenLite.to(breathe_txt_mc, 1,{alpha:0});

Answer 1

This error means that you are trying to access an object on display list that (object) is not there.
For example, if close_btn instance is not added as child, the following line will throw this error:
removeChild(close_btn);
One of the ways to remedy this is to confirm that the object is added:
if(contains(close_btn)) removeChild(close_btn);