[flexcoders] How do I use URLLoader?

[wild.katana]

I have this code: var myXML:XML = new XML();
var XML_URL:String =
"http://gdata.youtube.com/feeds/api/videos?vq=football+-soccer&orderby=published&start-index=11&max-results=10";;
var myXMLURL:URLRequest = new URLRequest(XML_URL);
var myLoader:URLLoader = new URLLoader(myXMLURL);
myLoader.addEventListener("complete", xmlLoaded);

function xmlLoaded(event:Event):void
{
    myXML = XML(myLoader.data);
    trace("Data loaded.");
}

And I want to read the XML file into a XML object in Flex, so that I
can access different elements of it easier. But it is throwing up two
errors when I try to compile it: 

1120: Access of undefined property myLoader.    
1120: Access of undefined property xmlLoaded.   

What am I doing wrong? Do I need to import any special things first? I
am still pretty new to Flex...