Access of undefined property (loader)

Question

I am trying to run the simple code as following:
<fx:Script>
<![CDATA[
                              import flash.display.*;
                              import flash.net.URLRequest;
                              Security.allowDomain("www.youtube.com");
                              var url2:String = "image2.jpg";
                              var urlRequest:URLRequest = new URLRequest(url2);   //problem code
                              var loader:Loader = new Loader();     //problem code
                              loader.contentLoaderInfo.addEventListener(Event.COMPLETE, loader_complete);   //problem code
                              loader.load(urlRequest);
                              addChild(loader);
                              function loader_complete(evt:Event):void {
                                        var target_mc:Loader = evt.currentTarget.loader as Loader;
                                        target_mc.x = (stage.stageWidth - target_mc.width) / 2;
                                        target_mc.y = (stage.stageHeight - target_mc.height) / 2;
                    ]]>
          </fx:Script>
However, I got errors saying
    'access of undefined property 'loader_complete'
    'access of undefined property 'loader'
    'access of undefined property 'loader'
    'access of undefined property 'loader'
    'access of undefined property 'urlReguest'
I haven't used Flash builder for a while and need some assistants. Any thoughts? Thanks for the help.

Answer 1

I am just testing some codes for youtube api. It seems like that I can't use the Loader Class properties. Not sure why.
I copied some code from the example in this website.
https://developers.google.com/youtube/flash_api_reference