[ragtek]

In your first code, $Zforum was not in the scope!
You can't use variables inside a function which are declared outsite withouth an global

PHP Code:

$Zforum = 5;

    private function fetch_lastids()
    {
global $Tforum;
        $lastx = $this->registry->db->query_first("
        SELECT COUNT(`threadid`) AS `lastx`
        FROM " . TABLE_PREFIX . "thread AS thread
        WHERE thread.forumid IN (0,". $Zforum. ")
        AND thread.visible = 1
        ");
        $this->threadscount = $lastx['lastx'];
    }