Problem installing the Nominatim web front-end

I am currently trying to set up a OSM Server together with Nominatim to do Reverse Geocoding. OSM works fine (I can render maps with Mapnik etc...)

I also set up the tables for Nominatim following this: https://wiki.openstreetmap.org/wiki/Nominatim/Installation#Set_up_the_website

But when I copy the website directory to /var/www/ and open the page, it will just show an empty page. (PHP-Parser works fine) I already hunted the problem down to a line in "init.php", where it says "require_once('DB.php');", but there is no DB.php in the website/.htlib/ directory. Is it missing, or where is this usually to be found?