Error #2007

[sholton311]

I'm trying to make an image gallery in actionscript 3.0. However, every time I start loading my thumbnail images, I get this error upon running:

TypeError: Error #2007: Parameter url must be non-null.
at flash.display::Loader/flash.display:Loader::_load()
at flash.display::Loader/load()
at your_gallery_fla::MainTimeline/loadTheThumbs()
at your_gallery_fla::MainTimeline/your_gallery_fla::frame1()

Can someone please tell me what this means, and why I'm getting this error? I'll include my script below so far:
========================================
import fl.transitions.Tween;
import fl.transitions.easing.*;

stage.scaleMode = "noScale";
stage.align = "TL";

var all_thumbs:MovieClip = new MovieClip();
addChild(all_thumbs);

var mainPicArea:MovieClip = new MovieClip();
addChild(mainPicArea);

galleryPane.source = all_thumbs;

var fadeIn:Tween;

var urlVar:String = "gallery.xml";

var picturePathList:Array = [];
var thumbPathList:Array = [];
var pictureTitleList:Array = [];
var pictureDescList:Array = [];

var totalPics:Number;

var mainPicPlacementX:Number;
var mainPicPlacementY:Number = 70;

var c:Number = 0;
var xSpacing:Number = 125;
var ySpacing:Number = 115;
var xs:Number = 0;
var ys:Number = 0;
var thumbRowCount:Number = 0;

var thumbOrientation:Number;

loadTheXML();
/*---Load the XML---*/

function loadTheXML() {
var xmlURLLoader:URLLoader = new URLLoader;
var xmlURLRequest:URLRequest = new URLRequest( urlVar );
xmlURLLoader.load( xmlURLRequest );
xmlURLLoader.addEventListener(Event.COMPLETE, sortTheXML);

function sortTheXML(event:Event):void{
var theXMLData:XML = new XML( xmlURLLoader.data );
var a:Number = theXMLData.picture_path.length();
totalPics = a;
var b:Number = 0;

while ( b < a ) {
picturePathList.push( theXMLData.picture_path[ b ] );
thumbPathList.push( theXMLData.thumb_path[ b ] );
pictureTitleList.push( theXMLData.picture_title[ b ] );
pictureDescList.push( theXMLData.picture_desc[ b ] );
b = b + 1;

var mainLoader:Loader = new Loader();
var mainRequest:URLRequest = new URLRequest( picturePathList[0] );
mainLoader.load(mainRequest);
mainLoader.contentLoaderInfo.addEventListener(Even t.COMPLETE, mainLoaded);

function mainLoaded(event:Event):void {
mainPicPlacementX = (stage.stageWidth / 2) - ( mainLoader.width / 2);
mainPicArea.x = mainPicPlacementX;
mainPicArea.y = mainPicPlacementY;
fadeIn = new Tween(mainPicArea, "alpha", None.easeNone, 0,1,30, false);
mainPicArea.addChild( mainLoader );

picTitle.text = pictureTitleList[ 0 ];
picDesc.text = pictureDescList[ 0 ];
picTitle.x = mainPicArea.x;
picDesc.x = mainPicArea.x;
picTitle.y = mainPicArea.y + mainPicArea.height + 5;
picDesc.y = mainPicArea.y + mainPicArea.height + 20;
picTitle.width = mainPicArea.width;
picDesc.width = mainPicArea.width;
}
}

}
}
loadTheThumbs();

function loadTheThumbs() {
var thumbLoader:Loader = new Loader();
var thumbRequest:URLRequest = new URLRequest( thumbPathList[ c ] );
thumbLoader.load( thumbRequest);
thumbLoader.contentLoaderInfo.addEventListener(Eve nt.COMPLETE, whenThumbsLoad);

function whenThumbsLoad(event:Event):void {




c = c + 1;
if ( c < totalPics) {
loadTheThumbs();
} else {
trace ( "done loading thumbs" );
}
}

}

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If anyone can help, I appreciate it in advance.

[adam2510]

what do you get when you trace picturePathList[0]

[sholton311]

It doesn't trace anything; I still get the same error