I'm working with eclipse, blazeds and Flex Plugin, and every time I create a Web Dynamic Project then add a Flex Project Nature to it this error: "An unknown item is declared as the root of your mxml document" appears just as the perspective view changes and I click on the design mode. As far as I know the only lines of code written on the screen are the standard in any other program, but I'll put here anyway so you can have a go at it if there's something realyy wrong and I didn't see:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
</mx:Application>