[flexcoders] creating instances, addChild question

[bhaq1972]

This question is very similar to a question someone else is asking 
(may even be the same thing????)

I've got a component called MyPrintView.mxml

<mx:VBox>
  <mx:Label id="contact"/>
  <mx:PrintDataGrid id="printDG"/>
</mx:VBox>


when i create an instance of MyPrintView, its children are not 
created. why is that?

if you addChild() to the Application....they are created. why is 
that?


<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"; 
initialize="startUP()">

    <mx:Script>
        <![CDATA[
            private function startUP():void
            {
              var printView:MyPrintView = new MyPrintView();
trace(printView);                               
trace(printView.printDG, printView.contact); //both null
              addChild(printView);            
trace(printView.printDG, printView.contact); //both not null

            }
        ]]>
    </mx:Script>
</mx:Application>