Erreur 500:  Class 'DOMDocument' not found in lib/AdService/Parser/AbstractParser.php

Hello,
Congrats @Blount  for this cool project! I have this error when trying to create a RSS:

    PHP Fatal error:  Class 'DOMDocument' not found in 
    /home/www/cheky/lib/AdService/Parser/AbstractParser.php on line 8, referer: 
    http://MONIP/cheky/?mod=rss

Otherwise, the admin panel is working, the var/ directory is writable, etc.

Any idea?
