Sto provando ad eseguire del javascript con flex 4, ed actionscript 3 ma non viene eseguito niente.

codice:
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="start();">
    
	<mx:Script>
	    
		<![CDATA[
			import flash.net.*;
			import flash.external.ExternalInterface;
			import flash.html.HTMLLoader;
			import mx.controls.Alert;
		     
			
				public function start():void {
			
					var html:HTMLLoader = new HTMLLoader;
					html.width = 400;
					html.height = 200;

					var urlReq:URLRequest = new URLRequest("http://www.google.com");

					html.load(urlReq);

					if(ExternalInterface.available){

					//Alert.show('ExternalInterface available');
					ExternalInterface.call("alert('This is javascript called by flex on linux')");

					} else {

						Alert.show('ExternalInterface is not available');

					}


				}

		]]>

	</mx:Script>

	<mx:Button id="button1" click="start()" label="START!" />

</mx:Application>
parte e non succede niente. La richiesta a google, non viene neanche eseguita, ho guardato con uno sniffer per le richieste http.
Che faccio?