Pb aprés l'installation de datalife engine

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/bashsoft/public_html/z4share.com/engine/modules/statistics.php on line 24

<?php
/*
=====================================================
 DataLife Engine 7.3 Full English By Arash.N
-----------------------------------------------------
 http://SyarashTools.com/
-----------------------------------------------------
 Pack By: http://English.DatalifeCMS.ir/
-----------------------------------------------------
 Copyright (C) 2006,2008 By DatalifeCMS (http://datalifecms.ir)
=====================================================
*/

define('ROOT_DIR', '..');
define('ENGINE_DIR', ROOT_DIR.'/engine');

require_once ENGINE_DIR.'/classes/mysql.php';
require_once ENGINE_DIR.'/data/dbconfig.php';
require_once ENGINE_DIR.'/modules/functions.php';

$day=date("j");

$query=  $db->query("SELECT * FROM " . USERPREFIX . "_today");
$num= mysql_num_rows($query);
for ($i=0; $i <$num; $i++) {
$row = mysql_fetch_array($query);

if ($day==$row[day]){
$db->query("UPDATE dle_today SET number=number+1,day='$day' ");
$db->query("UPDATE dle_total SET number=number+1 ");
} else {
$db->query("UPDATE dle_yesterday SET number=$row[number]");
$db->query("UPDATE dle_today SET number=1 , day='$day'");
} }

$row2 = $db->super_query("SELECT * FROM " . PREFIX . "_yesterday");
$yesterday = $row2['number'];

$row3 = $db->super_query("SELECT * FROM " . PREFIX . "_total");
$all = $row3['number'];

$statistics="&nbsp;&nbsp;Today: $row[number]<BR>&nbsp;&nbsp;Yesterday: {$yesterday}<BR>&nbsp;&nbsp;All Visits: {$all}";

?>