Hide application in taskbar, appear like a widget

Please! Help Me!

In a new Project of Adobe Flex/Air, I get error 1136.
This occurs when I add a new mxml file, with the code:

<mx:Window xmlns="http://ns.adobe.com/air/application/1.5"
           xmlns:fx="http://ns.adobe.com/mxml/2009"
            xmlns:mx="library://ns.adobe.com/flex/mx"
            width="200" height="100"
           transparent="true" systemChrome="none" type="normal"
           showStatusBar="false" showTitleBar="false" showFlexChrome="false">
    <mx:Label text="New Window"/> 
</mx:Window>

This give me the error:
1136: Incorrect number of arguments.  Expected 1.

There´s nothing else in the project.

I need to start the appliction without icon on taskbar, like a widget.

And I´ll use this mx:Window to open that like a new windows without appear in taskbar. I saw that in a tutorial, that don´t work!

Can you help me?