Problems with using a variable of type flash.filesystem.File

Question

I need to parse a file with my flex app.  I can import flash.filesystem.File with no problem but if I try to create a variable of that type, it does strange things at run time.  If the variable is defined inside a function, it's as if that function no longer exists.  The function doesn't get called and I can't step into it.  If I define a File variable at global scope, the swf simply won't do anything at all.
I've added all the AIR libs to my project and don't know what else to try at this point.  Any ideas?
This sample code shows the problem.  If I comment out the File in initData, initData doesn't get called and I can't step into it.  If I comment out the global File, then I get a blank swf.
<?xml version="1.0" encoding="utf-8"?>
<mx:Application           
   xmlns:mx="http://www.adobe.com/2006/mxml" minWidth="955" minHeight="600"
   initialize="initData()">
    <mx:Script>
        <![CDATA[
            import flash.filesystem.File;
            //private var file:File;
            private function initData():void
                //var file:File;  
                testLabel.text = "test";   
        ]]>
    </mx:Script>
    <mx:TextArea y="200" id="testLabel" text="hello" />
</mx:Application>

Answer 1

sorry for my ignorance, I've only been using flex since 4.0
shouldn't you be using WindowedApplication rather than Application for an AIR app?
also there is no need to import File
below is my code that work's fine
<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml"
                              layout="absolute"
                              initialize="initData()">
     <mx:Script>
          <![CDATA[
               private var file:File;
               private function initData():void
                    var file:File;
                    testLabel.text = "test";
          ]]>
     </mx:Script>
     <mx:TextArea y="200" id="testLabel" text="hello" />
</mx:WindowedApplication>