Generated webservices give null result in Flex 3

Question

Hi there,  I have a web service on my localhost. Calling this from a PHP page works fine and it returns the expected results. (I pass 2 values and it returns a different string depending on the values passed).
However, in Flex 3, I have generated the webservice proxy classes using the "Data" | "Manage Web Services" dialog.  I am consuming these services using the following code:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
     <mx:Button click="clickHandler(event)"/>
     <mx:Script>
          <![CDATA[
               import generated.webservices.*;
               import mx.controls.Alert;
               import mx.rpc.events.FaultEvent;
               public var _ws:SalesService = new SalesService();
               private function clickHandler(_e:MouseEvent):void
                    _ws.addonsaleEventListener(resultHandler);
                    _ws.addSalesServiceFaultEventListener(faultHandler);
                    _ws.onsale(10,90);
               public function resultHandler(_e:OnsaleResultEvent):void
                    if(_e.result == null)
                         Alert.show("result is: null");
                    else
                         Alert.show("result is: "+_e.result);
               public function faultHandler(_e:FaultEvent):void
                    Alert.show(_e.message.toString());
          ]]>
     </mx:Script>
</mx:Application>
The "resultHandler" method is called and the "faultHandler" method is not called, which suggests a result is returned, but _e.result is null in the "resultHandler" method.
Can anyone see if I am missing something in the actionscript?
Andrew.
p.s.
I can post the generated proxy classes, or even the wsdl for the webservice if it helps.
A.

Answer 1

No, they're not exactly the same (see below).
Calling the same web service; Flex 3 is generating a
different result object than Flex 2, and therefore can/will not
type the results as the Array my original app had come to expect.
Is this by design?
A suggested code revision would help, but...
The question in my
original post is still in play:
Where would I have gone to learn this? The release notes are
simply a cut list of changes. Is there a resource which summarizes
the types of errors one is likely to see when porting a Flex 2 app
to Flex 3, along with the most-likely changes as causes? When CFMX
was first released, there was a helpful checklist of tags and
syntax to help you audit your CF5 for the upgrade. Has one of your
gurus blogged something like this for FX3 and I just can't find it?