we need more info for this.
like how they make the torrent file
what php/mysql version you are using
is the code updated for those versions..and so on
the error is triggered by this bit of code from announce.php
PHP Code:
foreach (array("passkey","info_hash","peer_id","port","downloaded","uploaded","left") as $x)
if (!isset($$x))
err("Missing key: $x");