[Mediawiki-l] 1.6.2 navigation sidebar

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Hi again,

I have set $wgUseDatabaseMessages = false;  in my LocalSettings.php 
because I want to switch the languagecode from "de" to "en" some times.

The Wiki switch the complete language correctly from german to english 
and back, excepting the navigation sitebar, and i find no way to edit it 
(the wiki is always useing the german language in the navigation 
sidebar). Changes in the messages.php have no effect (I also can't add a 
navigation link).
The only Way I have found is delete $wgUseDatabaseMessages = false in 
the LocalSettings.php and use MediaWiki:Sidebar to edit it.

Is there no way to edit the Sidebar with $wgUseDatabaseMessages = false???
Why does have changes in Messages.php no effect?
Why does all the other Text switch from german to english excepting the 
navigation sidebar?

I have a fresh-installed 1.6.2 Wiki and have done the setup with the 
german language...
Then I logged in as an user and switch the language in preferences from 
german to english it will work all correctly.