Problema con mysql_result

[gaten]

Salve ragazzi ho un problema, ho creato il seguente script:

        
        include("class.php");
        $db = new Database;
        $db->connect();
        
        $sql = "SELECT * FROM news";
        $result = $db->query($sql) or die ("Errore query: " . mysql_error());
        
        $num_rows = $db->numRows();
        
        for ($k = 0; $num_rows > $k; $k++)
        {
              
            // Ricaviamo i valori
            $id = mysql_result($result, $k, 'id_news');
            $testo = mysql_result($result, $k, 'testo');
            $data = mysql_result($result, $k, 'data');
            
            if ($k % 2 == 0)
                $color = "#F2F2F2";
            else
                $color = "FFFFFF";
                
            echo "<p style=\"background-color: ".$color."\">";
            echo "[b]<img src=\"img/freccia.png\" width=\"13\" height=\"9\" />".$data."[/b]
";
            echo $testo;
            echo "</p>";
        } 

Non riesco a capire perchè mi dà il seguente errore:

Warning: mysql_result(): supplied argument is not a valid MySQL result resource in D:\Inetpub\webs\fitnutritionit\index.php on line 97

Warning: mysql_result(): supplied argument is not a valid MySQL result resource in D:\Inetpub\webs\fitnutritionit\index.php on line 98

Warning: mysql_result(): supplied argument is not a valid MySQL result resource in D:\Inetpub\webs\fitnutritionit\index.php on line 99

Ecco le righe 97,98 e 99:

$id = mysql_result($result, $k, 'id_news');
$testo = mysql_result($result, $k, 'testo');
$data = mysql_result($result, $k, 'data'); 

Grazie anticipatamente,
Gaten