Flash Builder 4.5.1 - Air ApplicationUpdaterUI Auto Update Fails

Question

I just reinstalled my FlashBuilder 4.5.1 and built a new HelloWorld App
in order to test the SDK 2.6 with the Air ApplicationUpdaterUI.
I get no errors but it won't update using the 2.6 namespace in both the -app.mxml and update.xml on server.
A trace in the StatusUpdateEvent never shows up in debug mode.
The only window that pops up is the one asking to Check for Update?
Pulling my hair out - must be something obvious I'm doing wrong here - can a new set of eyes spot something?
Main xml file:
<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
                       xmlns:s="library://ns.adobe.com/flex/spark"
                       xmlns:mx="library://ns.adobe.com/flex/mx"
                       creationComplete = "checkForUpdate();" title="Test Air Updater">
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>
    <fx:Script>
        <![CDATA[
            import air.net.URLMonitor;
            import air.update.ApplicationUpdaterUI;
            import air.update.events.StatusUpdateErrorEvent;
            import air.update.events.StatusUpdateEvent;
            import air.update.events.UpdateEvent;
            import flash.events.ErrorEvent;
            import mx.controls.Alert;
            import mx.events.CloseEvent;
            import mx.events.FlexEvent;
            private const APP_VERSION_FILE:String     = "http://www.public-knowledge.com/Quest/Timesheets/new_app_version.xml";
            private var appUpdater:ApplicationUpdaterUI = new ApplicationUpdaterUI();
            private function checkForUpdate():void {
                // Add events
                appUpdater.addEventListener(UpdateEvent.INITIALIZED, onInitialized);
                appUpdater.addEventListener(StatusUpdateErrorEvent.UPDATE_ERROR, onUpdateStatusError);
                appUpdater.addEventListener(StatusUpdateEvent.UPDATE_STATUS, updateStatusHandler); 
                appUpdater.addEventListener(ErrorEvent.ERROR, onError); // If something goes wrong, run onError               
                appUpdater.isCheckForUpdateVisible = true;
                appUpdater.isUnexpectedErrorVisible = true;
                appUpdater.isDownloadUpdateVisible= true;
                appUpdater.isDownloadProgressVisible=true;
                appUpdater.isInstallUpdateVisible = true;               
                appUpdater.updateURL = APP_VERSION_FILE; // Server-side XML file describing update               
                trace(APP_VERSION_FILE);
                appUpdater.initialize();
            private function onError(event:ErrorEvent):void {
                Alert.show('ERROR: ' + event.toString());
            private function onUpdateStatusError(event:StatusUpdateErrorEvent):void {
                Alert.show('Error Checking For Update: ' + event.toString());
            private function onInitialized(event:UpdateEvent):void {
                trace('Checking For Updates ...');       
                appUpdater.checkNow();
            private function updateStatusHandler(event:UpdateEvent):void {
                //var descriptor:XML = NativeApplication.nativeApplication.applicationDescriptor;
                //var ns:Namespace   = descriptor.namespaceDeclarations()[0];
                //var verNum:String  = descriptor.ns::versionNumber;
                trace('Update Event Reached ...');       
        ]]>
    </fx:Script>   
    <s:TitleWindow x="63" y="35" width="250" height="200" title="Hello">
        <s:Label x="24" y="80" text="Hello World"/>
    </s:TitleWindow>
</s:WindowedApplication>
-App.MXML File: (first part)
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<application xmlns="http://ns.adobe.com/air/application/2.6">
<!-- Adobe AIR Application Descriptor File Template.
    Specifies parameters for identifying, installing, and launching AIR applications.
    xmlns - The Adobe AIR namespace: http://ns.adobe.com/air/application/2.6
            The last segment of the namespace specifies the version
            of the AIR runtime required for this application to run.
    minimumPatchLevel - The minimum patch level of the AIR runtime required to run
            the application. Optional.
-->
    <!-- A universally unique application identifier. Must be unique across all AIR applications.
    Using a reverse DNS-style name as the id is recommended. (Eg. com.example.ExampleApplication.) Required. -->   
    <id>ca.questgeomatics.testairapp</id>
    <!-- Used as the filename for the application. Required. -->
    <filename>TestAirUpdater</filename>
    <!-- The name that is displayed in the AIR application installer.
    May have multiple values for each language. See samples or xsd schema file. Optional. -->
    <name>TestAirUpdater</name>
    <!-- A string value of the format <0-999>.<0-999>.<0-999> that represents application version which can be used to check for application upgrade.
    Values can also be 1-part or 2-part. It is not necessary to have a 3-part value.
    An updated version of application must have a versionNumber value higher than the previous version. Required for namespace >= 2.5 . -->
    <versionNumber>1.0.0</versionNumber>
    <!-- A string value (such as "v1", "2.5", or "Alpha 1") that represents the version of the application, as it should be shown to users. Optional. -->
    <versionLabel>v 1.0.0</versionLabel>
Updater XML file (new_app_version.xml):
<?xml version="1.0" encoding="utf-8"?>
<update xmlns="http://ns.adobe.com/air/framework/update/description/2.6">
<versionNumber>1.0.1</versionNumber>
<versionLabel>v 1.01</versionLabel>
<url>http://www.public-knowledge.com/Quest/Timesheets/TestAirUpdater.air</url>
<description><![CDATA[
* First official release that implemements Auto Updating feature
]]></description>
</update>
Bolded appl descriptor versions
Message was edited by: DonMitchinson

Answer 1

Status Update - don't know if this is a bug, design flaw, install problem or my misunderstanding.
I got it to work by first changing my Flex library to 4.5.0 - still didn't work with current
app and update mxml files using "2.6" for their namespace versions. But I did at least
get the popup error number 16815 - indicating an error in the update version namespace.
By leaving my application namespace version at "2.6" and changing the update version to "2.5" ... bingo!
I got my new update installed autiomatically.
Is this how it's supposed to work - or are my runtimes mixed up?
Will this work the same using the Flex 4.5.1 SDK? I'll find out shortly
Hope this helps others.