Flickr api problem

Hi,
Im just getting started with the flickr api, I have been trying with out any real success to get some xml loaded from the url from flickr just to get started I created an account etc. and followed a few tutorials but I cant get it working i just want to load the xml and go from there. If I put the XML_FlickrBase into a browser it shows the xml I understand I need.


package 
{
 import flash.display.*;
 import flash.net.*;
 import flash.events.*;
 import flash.display.MovieClip;
 import flash.system.*;
 Security.allowDomain("*", "api.flickr.com");
 public class Main extends MovieClip
 {
  public var key:String = "";//your flickr api key
  public var per_page:int = 50;
  public var page:int = 1;
  public var XML_FlickrBase:String = "http://api.flickr.com/services/rest/?method=flickr.photos.search&api_key=55dfc60e3919574ef151057db60bdbb0&tags=cats";
  public var currentURL:String;
  public var myXMLRequest;
  public var myXMLLoader;
  public function Main()
  {
   // constructor code
   getRecentPhoto();
  }
  function loadImage(img_src:String)
  {
  }
  function getRecentPhoto():void
  {
   currentURL = XML_FlickrBase;
   myXMLLoader = new URLLoader(myXMLRequest);
   myXMLLoader.addEventListener("complete", showFirstPhoto);
  }
  function showFirstPhoto(event:Event):void
  {
   var myXML:XML = new XML(myXMLLoader.data);
   trace(myXML.toXMLString());
   test.text = myXML.toXMLString();
   trace('myXML.toXMLString(): ' + myXML.toXMLString());
  }
 }
}

Can any one help get me on the right track?