Could not resolve <Application> to a component implementation.

Hi..

Am getting an error message Could not resolve <Application> to a component implementation. Am trying the following mxml code.

<?xml version="1.0" encoding="utf-8"?>

<!-- http://blog.flexexamples.com/2008/08/25/saving-files-locally-using-the-filereference-classs-save-method-in-flash-player-10/ -->

<Application name="FileReference_save_test"

        xmlns="http://ns.adobe.com/mxml/2009"

        xmlns:mx="library:adobe/flex/halo"

        xmlns:net="flash.net.*"

        layout="flex.layout.BasicLayout"

        creationComplete="init();">

    <Script>

        <![CDATA[

            private function init():void {

                textArea.text = describeType(FileReference).toXMLString();

            }

            private function btn_click(evt:MouseEvent):void {

                fileReference.save(textArea.text, "describeType.txt");

            }

        ]]>

    </Script>

    <Declarations>

        <net:FileReference id="fileReference" />

    </Declarations>

    <mx:Panel id="panel"

            width="500"

            height="300"

            verticalCenter="0"

            horizontalCenter="0">

        <mx:TextArea id="textArea"

                editable="true"

                width="100%"

                height="100%" />

        <mx:ControlBar horizontalAlign="right">

            <Button id="btn"

                    label="Save Text"

                    click="btn_click(event);" />

        </mx:ControlBar>

    </mx:Panel>

</Application>..

Help plz..