Cant load an image

I cant load an image in the document class.
Do I need to load all images from a class as I cant load images in a Document class directly?

With this code I get a

Error #1009: Cannot access a property or method of a null object reference.
at Main/moveright()
at Main/doSomething()


// Class   public class Main extends MovieClip {       // Variables       private var noLoaded:int;           var myText:TextField = new TextField();        private   var img1:Bitmap;                  // Constructor       public function Main():void {                      // Stage set up           stage.align=StageAlign.TOP_LEFT;           stage.scaleMode=StageScaleMode.NO_SCALE;           stage.quality=StageQuality.BEST;           stage.displayState=StageDisplayState.NORMAL;           stage.frameRate=30;                                     // Init load counter             noLoaded=0;                      // Create a ClassImg6 instance                                              // Add stage listeners                      stage.addEventListener(Event.ENTER_FRAME,gameLoop,false,0,true);             stage.addEventListener(KeyboardEvent.KEY_DOWN,doSomething,false,0,true);                                                    myText.text = "The quick brown fox jumps over the lazy dog";               addChild(myText);                myText.border = true;               myText.wordWrap = true;               myText.width = 150;               myText.height = 40;               myText.x = 200;               myText.y = 10;           var loader:Loader = new Loader;            loader.contentLoaderInfo.addEventListener(Event.COMPLETE, imageLoaded);            loader.load(new URLRequest("scave4.png"));                                 }            private function imageLoaded(event:Event):void          {                                var img1:Bitmap = new Bitmap(event.target.content.bitmapData);               //img1.bitmapData = bmd;               addChild(img1);               img1.y=100;               img1.x=100;                                                 noLoaded++;          }                                  function moveleft()          {     img1.x-=5;     }                    function moveright()          {     img1.x+=5;     }                     function moveup()          {     img1.y-=5;     }                     function movedown()          {     img1.y+=5;     }                                     function doSomething(e:KeyboardEvent):void {           if (e.keyCode==37) { moveleft(); }// Left                        if (e.keyCode==39) {                  moveright();                   trace("rigfht");                  }// Right                               if (e.keyCode==38) {moveup(); }// Left           if (e.keyCode==40) { movedown(); }// Right