Session wil niet werken

session_start();
ob_start();

error_reporting(E_ALL);
ini_set("display_errors", 1);
/*
verborgen db gegevens...
*/


mysql_connect($dbhost, $dbuser, $dbpass);
mysql_select_db($dbname);

include('includes/functions.php');
include('includes/classes/highscores.class.php');
include('includes/classes/user.class.php');
include('includes/classes/item.class.php');

session_start();
ob_start();
 
error_reporting(E_ALL);
ini_set("display_errors", 1);
/*
verborgen db gegevens...
*/
 
 
mysql_connect($dbhost, $dbuser, $dbpass);
mysql_select_db($dbname);
 
include('includes/functions.php');
include('includes/classes/highscores.class.php');
include('includes/classes/user.class.php');
include('includes/classes/item.class.php');

<h6><span>I</span>nloggen</h6>
<?
if(isLogged() == false){
	$_SESSION['user_id'] = 1;
	echo "Je bent nu ingelogd!";
}else{
	echo "Je bent al ingelogd!";
}
?>
<script>
gaNaar('index');
</script>

<h6><span>I</span>nloggen</h6>
<?
if(isLogged() == false){
	$_SESSION['user_id'] = 1;
	echo "Je bent nu ingelogd!";
}else{
	echo "Je bent al ingelogd!";
}
?>
<script>
gaNaar('index');
</script>

<?
function isLogged(){
	if(isset($_SESSION['user_id'])){
		return true;	
	}else{
		return false;	
	}
}
?>

<?
function isLogged(){
	if(isset($_SESSION['user_id'])){
		return true;	
	}else{
		return false;	
	}
}
?>

<div class="header" onClick="menu('gebruiker');">
  <h1>Leden</h1>
</div>
<div class="sidebarboxGebruiker" id="gebruiker">
<?
	if(isLogged() == false){
?>
<form action="?p=login" method="post">
Gebruikersnaam:<br />
<input name="username" class="field" type="text" /><br />
Wachtwoord:<br />
<input name="pass" class="field" type="password" /><br />
<input name="submit" type="submit" value="login" /></form><br />
<a href="javascript:alert('Deze login feature is tijdelijk alleen beschikbaar voor de crew');">Nog geen account?</a><br />
<a href="javascript:alert('Je hebt nog geen account, je hebt dus nog geen account.');">Wachtwoord vergeten?</a><br />
<?	
}else{
	$user = new Users($_SESSION['user_id']);
?> 
	<?=momentOfDay(); ?>, <?=$user->username(); ?>!<br />
	<a href="?p=logout">Uitloggen</a>

<?
	}
?>
</div>

<div class="header" onClick="menu('gebruiker');">
  <h1>Leden</h1>
</div>
<div class="sidebarboxGebruiker" id="gebruiker">
<?
	if(isLogged() == false){
?>
<form action="?p=login" method="post">
Gebruikersnaam:<br />
<input name="username" class="field" type="text" /><br />
Wachtwoord:<br />
<input name="pass" class="field" type="password" /><br />
<input name="submit" type="submit" value="login" /></form><br />
<a href="javascript:alert('Deze login feature is tijdelijk alleen beschikbaar voor de crew');">Nog geen account?</a><br />
<a href="javascript:alert('Je hebt nog geen account, je hebt dus nog geen account.');">Wachtwoord vergeten?</a><br />
<?	
}else{
	$user = new Users($_SESSION['user_id']);
?> 
	<?=momentOfDay(); ?>, <?=$user->username(); ?>!<br />
	<a href="?p=logout">Uitloggen</a>
 
<?
	}
?>
</div>