i've modified the code to automatically use the correct method, attached the fixed copy, can be used on any forum since i've added in the conditional, heres a example of that i've added
PHP Code:
if($vbulletin->config['Database']['dbtype']=='mysqli' OR $vbulletin->config['Database']['dbtype']=='mysqli_slave')
$usercount = mysqli_num_rows($result);
else
$usercount = mysql_num_rows($result);