Problems loading swf

1

Hi Everyone,
I have 2 swf. The first one is a preloader, the second one is my main swf (bg.swf).
So I have this error:
TypeError: Error #1009: Cannot access a property or method of a null object reference at bg_fla::MainTimeline/frame1()

    import flash.display.*;
    import flash.events.*;
    import flash.net.*;
    import caurina.transitions.*;

            stage.align = StageAlign.TOP_LEFT;
            stage.scaleMode = StageScaleMode.NO_SCALE;
            stage.addEventListener(Event.RESIZE, onResize);
			position();
			
        function position() : void
        {
            var _loc_1:* = stage.stageWidth / 2;
            var _loc_2:* = stage.stageHeight / 2;
            mc.x = _loc_1;
            mc.y = _loc_2;
            bg_mc.x = _loc_1;
            bg_mc.y = _loc_2;
            bg_mc.width = stage.stageWidth;
            bg_mc.height = stage.stageHeight;
												
            if (bg_mc.scaleX <= bg_mc.scaleY)
            {
                bg_mc.scaleX = bg_mc.scaleY;
            }
            else
            {
                bg_mc.scaleY = bg_mc.scaleX;
            }
            return;
        }

        function onResize(event:Event) : void
        {
            position();
            return;
        }

var loader:Loader = new Loader();
loader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onLoading);
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onComplete);
loader.load(new URLRequest("bg.swf"));

function onLoading(e:ProgressEvent):void
{
	var perc:Number = e.bytesLoaded / e.bytesTotal;
	mc.percent.text = Math.ceil(perc*100).toString();
}

function onComplete(e:Event):void
{
	Tweener.addTween(mc,{alpha:0,time:3,transition:"easeIn"});	
	removeChildAt(0);
	mc.percent = null;
	addChild(loader);
}

			var cm:ContextMenu=new ContextMenu();
			var design:ContextMenuItem=new ContextMenuItem("");
			var client:ContextMenuItem=new ContextMenuItem("PRESS:"");

			cm.hideBuiltInItems();
			cm.customItems.push(design, client);

			design.addEventListener(ContextMenuEvent.MENU_ITEM_SELECT,designHandler);
			client.addEventListener(ContextMenuEvent.MENU_ITEM_SELECT,clientHandler);

			contextMenu=cm;
			
		function designHandler(event:ContextMenuEvent):void 
		{
		var url:String="";
		var request:URLRequest=new URLRequest(url);
		navigateToURL(request,'_parent');
		}
			
		function clientHandler(event:ContextMenuEvent):void 
		{
			var url:String="";
			var request:URLRequest=new URLRequest(url);
			navigateToURL(request,'_parent');
		}

bg.swf:

   stop();
   
    import flash.display.*;
    import flash.events.*;
    import flash.net.*;
    import caurina.transitions.*;

            stage.align = StageAlign.TOP_LEFT;
            stage.scaleMode = StageScaleMode.NO_SCALE;
            stage.addEventListener(Event.RESIZE, this.resizeHandler);
			position();
			
        function position() : void
        {
            var _loc_1:* = stage.stageWidth / 2;
            var _loc_2:* = stage.stageHeight / 2;
			logo.x = stage.stageWidth / 2;
			logo.y = stage.stageHeight;
			logo.width = stage.stageWidth;
			upper.x = stage.stageWidth / 2;
			upper.y = stage.stageHeight / 2;
			upper.width = stage.stageWidth;
			menu.x = stage.stageWidth / 2;
			menu.y = stage.stageHeight - logo.height / 2;
			bg_mc.height = stage.stageHeight;
			bg_mc.width = stage.stageWidth;
			bg_mc.x = _loc_1;
			bg_mc.y = _loc_2;
			
/*			var randomNumber:Number = Math.ceil(Math.random()*10);

			trace (randomNumber);

			bg_mc.source = "images/Bkgd"+randomNumber+".jpg";
*/			
			
            if (bg_mc.scaleX <= bg_mc.scaleY)
            {
                bg_mc.scaleX = bg_mc.scaleY;
            }
            else
            {
                bg_mc.scaleY = bg_mc.scaleX;
            }
			
			Tweener.addTween(menu, {alpha:1, time:2, delay:2.5});
			Tweener.addTween(bg_mc, {alpha:1, time:2, delay:1});
			Tweener.addTween(logo, {alpha:0.7, time:2, delay:1.5});
			//Tweener.addTween(upper, {alpha:0.7, time:2, delay:1.5});
			return;
        }

        function resizeHandler(event:Event) : void
        {
            position();
            return;
        }

Thanks guys!

M.