Flash builder Event metadata not recognized

Question

Hello,
Can someone explain me why my event isn't recognized in the code below (it is not proposed as a property for my TestButton and if I try to force it I get an error)
Test application :
<?xml version="1.0" encoding="utf-8"?><s:Application 
xmlns:fx=http://ns.adobe.com/mxml/2009
xmlns:s="
library://ns.adobe.com/flex/spark"
xmlns:mx="
library://ns.adobe.com/flex/halo"
xmlns:local="
minWidth="
1024" minHeight="768"> 
    <local:TestButton/>
</s:Application>
TestButton.mxml :
<?xml version="1.0" encoding="utf-8"?>
<s:Button  
xmlns:fx=
http://ns.adobe.com/mxml/2009 xmlns:s="
library://ns.adobe.com/flex/spark"xmlns:mx="
library://ns.adobe.com/flex/halo">
     <fx:Metadata>  
Event("testEvent", type="flash.events.Event")]
     </fx:Metadata> </s:Button> 
There is no more or less code than that. I'm using the beta of Flash Builder 4.
Thanks. </s:Button> 
There is no more or less code than that. I'm using the beta of Flash Builder 4.
Thanks.
</s:Button>
There is no more or less code than that. I'm using the beta of Flash Builder 4.
Thanks.   

Answer 1

My apologize for my post layout but I definitly can't get my post to look like what I write in the text field. I don't know why it has repeated the last line (maybe because it's some Adobe stuff). It's difficult to be confident in the reliability of Adobe developping tools when a simple web page doesn't work correctly.
Sorry for being nasty but I'm starting to get rid of spending hours on ununderstandable problems.
(To be more nasty, the best this morning : I start a new Flex project in Flash Builder, make a few things, and when I tried to launch it, surprise : "This file cannot be launched" and that's all, no more explanation, imposible to find answer on the web. I finally had to restart the project.)