[absofts]

I include a file but its showing me this error

Fatal error: Call to a member function query_read_slave() on a non-object in /home/content/i/c/o/icompany/html/forum/verified.php on line 4

--------------- Added [DATE]1324635016[/DATE] at [TIME]1324635016[/TIME] ---------------

My file code is

PHP Code:

<?php
require_once('includes/class_paid_subscription.php');

$susers = $db->query_read_slave("
    SELECT *
    FROM " . TABLE_PREFIX . "subscriptionlog
    WHERE status = 1
    AND userid = " . $vbulletin->userinfo['userid']
);
$isPremium = $db->num_rows($susers);
if ($isPremium != 0){
    $st = '1';
}else{
    $st = '0';
}
    echo $st;

?>