application qui affiche rien

bonjour,
pourquoi mon application n'affiche rien :

Code:

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<?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/mx"
			   pageTitle="formation 1"
			   minWidth="955" minHeight="600"
			   creationComplete="application1_creationCompleteHandler(event)">
	<fx:Script>
		<![CDATA[
			import spark.components.Label;
			import mx.events.FlexEvent;
			import mx.controls.Alert;
 
			protected var myActionScriptText:Label;
 
			protected function application1_creationCompleteHandler(event:FlexEvent):void
			{
				Alert.show('');
			}
 
		]]>
	</fx:Script>
 
	<fx:Declarations>
		<!-- Place non-visual elements (e.g., services, value objects) here -->
 
	</fx:Declarations>
	<s:Button left="30" top="36" width="267" height="51" label="Button"/>
</s:Application>

il n'affiche pas l'alert
et il n'affiche pas le bouton
une page blanche sur firefox et chrome