[flexcoders] Newbie createPopUp problems

[fredsells]

I've copied various examples of using PopUpManager.createPopUp but
cannot get it to work.  I'm running from Eclipse using the flex Eclipse
plug-in under XP.  Eclipse does not show any errors (i.e. red marks) in
either file, but when I run I get a dialog "Errors exist in required
application".

I have tried creating a new project and still have the same problem.  I
have been searching for 2 days now and cannot find a clue.  My code is
below.

Is there some way to get better debug/diagnostic info in this case.  Can
anyone see what's wrong?

zflex001.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"; >
    <mx:Script>
    <![CDATA[
    import dialog;
    function openDialog():Void {
       var popupParent:zflex001 = this;
       var isModal:Boolean = true;
       var initObj:Object = { title:"Delete Record" };
       var verifyPopUp = mx.managers.PopUpManager.createPopUp(
popupParent, dialog, isModal, initObj );
    }
    ]]>
    </mx:Script>
    <mx:Button label="Verify" click="openDialog();" />
</mx:Application>

dialog.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:TitleWindow xmlns:mx="http://www.adobe.com/2006/mxml"; width="300"
height="120" title="Verify Action" >
    <mx:Label id="lblVerify" text="Are you sure you want to do this?" />
    <mx:HBox>
       <mx:Button label="Ok" />
       <mx:Button label="Cancel"  />
    </mx:HBox>
</mx:TitleWindow>