[flexcoders] why I can not dispatchEvent with creationComplete?

[markflex2007]

I try the following code, But I can not dispatchEvent.

<mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml";
creationComplete="justLogin()" >
<mx:Metadata>
        [Event(name="loginEvent", type="flash.events.Event")]
</mx:Metadata>
<mx:Script>
        <![CDATA[
                             
             
             private function justLogin():void{                
                 
                dispatchEvent(new Event("loginEvent", false));
             
             }
]]>
</mx:Script>    

</mx:Canvas>

I can  dispatchEvent with button click, please let me know how to
automatic  dispatchEvent in page start.

Thanks

Mark