FileStream problem with AIR deployment

Question

I use FileStream to load local XML file. When I test the desktop application directly from Flex everything is ok but when I install it with AIR, the application work but the file is not loaded. Here is the code I use:
import flash.filesystem.*;
 var applicationDirectoryPath:File = File.applicationDirectory; 
var nativePathToApplicationDirectory:String = applicationDirectoryPath.nativePath.toString(); 
nativePathToApplicationDirectory +=
"/config_poste_temps.xml"; 
var file:File = new File(nativePathToApplicationDirectory); 
var fs:FileStream = new FileStream(); 
fs.open(file, FileMode.READ);
var config:XML = XML(fs.readUTFBytes(fs.bytesAvailable)); 
fs.close();
plan.text = config.division;
Regards

Answer 1

I am having the same problem as simon_lucas although my config is slightly different:
FlashBuilder 4 with SDK 4.6, Current app is with SDK 2.5.
Trying to update with SDK 3.2, I double-checked per Horia Olaru that I do use the application updater swc:
         <path-element>D:\Program Files\Adobe\Adobe Flash Builder 4.6\sdks\4.6.0 - Air 3.2\frameworks\libs\air\applicationupdater.swc</path-element>
         <path-element>D:\Program Files\Adobe\Adobe Flash Builder 4.6\sdks\4.6.0 - Air 3.2\frameworks\libs\air\applicationupdater_ui.swc</path-element>
But I still have the 16815 error.
If I change the update.xml to be <update xmlns="http://ns.adobe.com/air/framework/update/description/2.5">
instead of <update xmlns="http://ns.adobe.com/air/framework/update/description/3.2">, I am proposed to download the new app and then I get an error 16824.
Please HELP!