Error 2124 with XML files

I am attempting to load an XML file using AS3.  I have seen several topics similar to my question, but none seem to fit my situation.   My code snippets follow.

        public function loadDirectory():void  {

            trace("THERE")   

            var setUpLoader:URLLoader = new URLLoader();

            setUpLoader.addEventListener(Event.COMPLETE, setupLoaded);

            setUpLoader.load(new URLRequest("xml/setup.xml"));

        }

        private function setupLoaded(e:Event)  {

            _setUpXML = XML(e.target.data);

            trace("HERE "+_setUpXML)

            completeLoading();

        }

Between the THERE trace and the HERE trace, I get the following error messages:

Error #2044: Unhandled IOErrorEvent:. text=Error #2124: Loaded file is an unknown type.

Error #2044: Unhandled IOErrorEvent:. text=Error #2124: Loaded file is an unknown type.

The initial snippet of my XML file is:

<?xml version="1.0" encoding="utf-8"?>

<setUp>

    <setdata rootdir="http://aln.coe.ttu.edu/anderson/T-Model11-0/" server="true" />

    <fonts> Arial,Helivetica,_sans </fonts>                    //--Font

    <fontsize> 12 </fontsize>                                //--Font size (Do not change)

The threads I have followed suggest the problem is using a Loader rather then a URLLoader.  But, my code uses the URLLoader.  Any suggestions are appreciated.