In /includes/functions.php: on line 1171 remove the table_prefix before $idname.
PHP Code:
if (!$check = $DB_site->query_first("SELECT $selid FROM " . TABLE_PREFIX . "$idname WHERE $idname" . "id=$id"))
this is what it look like after according to your explination
PHP Code:
if (!$check = $DB_site->query_first("SELECT $selid FROM " "$idname WHERE $idname" . "id=$id"))
is that correct?