Thread:Extension talk:Lingo/Magic word 'noglossary' not found

We are running MediaWiki 1.5.1 using PHP 5.2.6-1+lenny13 (apache2handler). After I installed the extension all pages showed an internal error with the headline "magic word 'noglossary' not found". In the backtrace 23 points were listed pointing to certain lines in files such as MagicWord.php, Parser.php and Cite.php. Extension:Terminology, however, works fine. Could someone explain the reasons, in case other people run into the same problem? Thanks,