as3 CS4 web service

I have a problem with using the webservice component from flex 3 in flash cs4.
I am making the same thing what is in this adobe tutorial:…-cs4-projects/

public function Main() 
            _WS = new WebService();

            _st = new String("");
            _WS.addEventListener("load", wsLoaded);
        private function Klik(e:MouseEvent):void 
        public function wsLoaded(e:LoadEvent):void 
            _myOperation = Operation(_WS.getOperation("GetCountries"));
            _myOperation.addEventListener("fault", wsError, false, 0, true);
            _myOperation.addEventListener("result", wsResult, false, 0, true);
        public function wsResult(e:ResultEvent):void 
            var xml:XML = new XML(e.result);
        public function wsError(e:FaultEvent):void 

And I’m getting tis Error:
Error opening URL ‘

If i open my swf in browser everything is fine.
Is ther something that can block the communication ?