Guestbook send php

<?php
include "classes.php";
ob_start();
$mysql = new mysql();
$mysql->connect();
$guestbook = new guestbook();

if(isset($_REQUEST["send"])){
$user = $guestbook->secure($_REQUEST["user"]);
$comment = $guestbook->secure($_REQUEST["comment"]);
if(empty($user) or empty($comment)){
echo "Please fill out all fields";
}
else{
$guestbook->newentry($user,$comment);
header('Location: index.php');
}
}
?>