Strange "INavigatorContent" error compiling in 4.0

Question

I've recently decided to try an upgrade to 4.0. The only error I still can't work out is this one:

"The children of Halo navigators must implement INavigatorContent"

I seem to be getting it on all my ViewStacks that have validators.

<mx:ViewStack xmlns:mx="http://www.adobe.com/2006/mxml"&gt;
 <mx:NumberValidator id="systolicValidator"
      source="{systolic}"
      required="true"
         property="text"
      minValue="10"
      maxValue="300"
      domain="int"/>
 <mx:NumberValidator id="diastolicValidator"
      source="{diastolic}"
      required="true"
      property="text"
      minValue="10"
      maxValue="200"
      domain="int"/>
    <mx:TextInput id="systolic"/>
        <mx:TextInput id="diastolic"/>
...
      </ViewStack> 

The error gets thrown on the validator tags. My compiler is set to "flex 3 compatibility mode" and my theme is set to Halo (default).

This seems like it should be a really straight forward fix, so I hate to spin my wheels on it for too long.

Any ideas what I might be missing?

Answer 1

After some reading about Flex 4, it would seem that all non-visual elements should go in these tags:

<fx:Declarations>
    <!-- Place non-visual elements (e.g., services, value objects) here -->
</fx:Declarations>

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

The error was kinda strange. However, after some cleanup, I got a better error:

'*' declaration must be contained within the <Declarations> tag since it does not implement 'mx.core.IUIComponent'.

Much, much more helpful. I'll post again if I find the reason for the strange error I was getting before.

Answer 2

http://bharatria.wordpress.com/2010/05/09/migration-from-flex-3-to-flex-4/

That is a great link that I found while updating my app from flex 3 to 4. It can be a bit of a headache, and I recommend reading up on Spark and Halo and all that stuff.