Error #1009: Cannot access a property or method of a null object reference

[Erickk]

I can't solve this, i need help.

I am trying to load another b.swf into this a.swf
if i try to load a swf without class it works fine.
a.swf have no class, but b.swf have.
I encounter this error.

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at MyGame()

What is the solution?
a.fla

stop();

function startLoad()
{
var imageRequest:URLRequest = new URLRequest("b.swf");
var imageLoader:Loader = new Loader();
imageLoader.load(imageRequest);
addChild(imageLoader);
}

function onCompleteHandler(loadEvent:Event)
{
        addChild(loadEvent.currentTarget.content);
}
function onProgressHandler(mProgress:ProgressEvent)
{
var percent:Number = mProgress.bytesLoaded/mProgress.bytesTotal;
trace(percent);
}
startLoad();

Mygame.as

package {
    import flash.display.MovieClip
    import flash.display.Sprite
    import flash.display.Bitmap
    import flash.display.BitmapData
    import flash.display.Graphics
    import flash.events.Event
    import flash.events.MouseEvent
    import flash.utils.ByteArray
    import flash.utils.setInterval
    import flash.utils.setTimeout
    import flash.geom.Point
    import flash.text.TextField
    import flash.display.BlendMode
    import flash.display.StageScaleMode
    import flash.display.StageAlign
    import flash.text.TextFormat
    
    import playerio.*
    import sample.ui.Prompt
    import sample.ui.Chat
    import sample.ui.Lobby
    
    public class MyGame extends MovieClip{
        private var connection:Connection
        private var lobby:Lobby
        private var questions:Array=new Array();
        private var answers:Array=new Array();

        [Embed(source="c.xml", mimeType="application/octet-stream")]
        private static const MyData:Class;
        
        function MyGame(){
            stop();
            
            
            PlayerIO.connect(
                stage,                                //Referance to stage
                "quiz-sfhwfbj70ectvbcjazv2tw",    //Game id (Get your own at playerio.com)
                "public",                            //Connection id, default is public
                "name",                        //Username
                "",                                    //User auth. Can be left blank if authentication is disabled on connection
                handleConnect,                        //Function executed on successful connect
                handleError                            //Function executed if we recive an error
            );  
            stage.scaleMode = StageScaleMode.NO_SCALE
            stage.align = StageAlign.BOTTOM
        }
        
        private function handleConnect(client:Client):void{
            trace("Sucessfully connected to player.io");
            
            //Set developmentsever (Comment out to connect to your server online)
            client.multiplayer.developmentServer = "localhost:8184";
            
            //Create pr join the room test
            client.multiplayer.createJoinRoom(
                "",                            //Room id. If set to null a random roomid is used
                "bounce",                            //The game type started on the server
                false,                                //Should the room be visible in the lobby?
                {},                                    //Room data. This data is returned to lobby list. Variabels can be modifed on the server
                {},
                handleJoin,                            //Function executed on successful joining of the room
                handleError                            //Function executed if we got a join error
            );
            //Create lobby
            lobby = new Lobby(client, "mygame", handleJoin, handleError)

            //Show lobby (parsing true hides the cancel button)
            lobby.show(true);
        }
        
        
        private function handleJoin(connection:Connection):void{
            trace("Sucessfully connected to the multiplayer server");
                        
            var byteArray:ByteArray = new MyData() as ByteArray;
            var xml:XML = new XML(byteArray.readUTFBytes(byteArray.length));
            var loop = 5;
            
            for (var i=0;i<loop;i++)
            {
                questions[i]=xml.ques[i].q1;
                //questions[i]=loop;
                answers[i]=[xml.ques[i].op1,xml.ques[i].op2,xml.ques[i].op3];
                //answers[i]=loop;
            }
            gotoAndStop(2);
            stop();

            /*
            trace(questions[1]);
            trace(answers[1]);
            trace(answers[1][0]);
            trace(answers[1][1]);
            trace(answers[1][2]);
            */
                        //Add chat to game
            var chat:Chat = new Chat(stage, connection);
            
            //Add listener for messages of the type "hello"
            connection.addMessageHandler("hello", function(m:Message){
                trace("Recived a message with the type hello from the server");            
            })
            
            //Add message listener for users joining the room
            connection.addMessageHandler("UserJoined", function(m:Message, userid:uint){
                trace("Player with the userid", userid, "just joined the room");
            })
            
            //Add message listener for users leaving the room
            connection.addMessageHandler("UserLeft", function(m:Message, userid:uint){
                trace("Player with the userid", userid, "just left the room");
            })
            
            //Listen to all messages using a private function
            connection.addMessageHandler("*", handleMessages)
            
        }
        
        private function handleMessages(m:Message){
            trace("Recived the message", m)
        }
        
        private function handleDisconnect():void{
            trace("Disconnected from server")
        }
        
        private function handleError(error:PlayerIOError):void{
            trace("got",error)
            gotoAndStop(4);

        }
    }    
}

[caseyryan]

You have this function where you call "load()" method

stop();

function startLoad()
{
var imageRequest:URLRequest = new URLRequest("b.swf");
var imageLoader:Loader = new Loader();
imageLoader.load(imageRequest);
addChild(imageLoader);
}

function onCompleteHandler(loadEvent:Event)
{
        addChild(loadEvent.currentTarget.content);
}
function onProgressHandler(mProgress:ProgressEvent)
{
var percent:Number = mProgress.bytesLoaded/mProgress.bytesTotal;
trace(percent);
}
startLoad();

But where's the event listener for the loader.contentLoaderInfo object?

[5TonsOfFlax]

The error is caused by the use of stage in the constructor for MyGame. The stage property is null until the instance is added to the display list, and it can't be added to the display list until after it's created. Flash cheats a bit when you use a class as a document class, so it works there, but not when loading into a loader.

Use an event listener for ADDED_TO_STAGE and do all your stage dependent initialization in there.