Error back to page

saya punya 3 halaman php dimana halaman 1 akan post ke halaman 2 dan dari halaman 2 post ke halaman 3 untuk ditampilkan. saat di halaman 3 ingin kembali ke halaman 2 terjadi eror.. bisa dilihat digambar berikut :

script page 1

 <?php
include 'libraries/config.php';
if(!isset($_SESSION))
    {
        session_start();
    }
if($_SESSION['id-cus']==''){
  header('location: login.php');
}
?>
<form action="2.php" method="POST">
	<table>
		<tr>
			<td>Name</td>
			<td><input type="text" name="name"></td>
		</tr>
		<tr>
			<td>Address</td>
			<td><input type="text" name="address"></td>
		</tr>
		<tr>
			<td></td>
			<td><button type="submit">Enter</button></td>
		</tr>
	</table>
</form>

page 2

<?php
include 'libraries/config.php';
if(!isset($_SESSION))
    {
        session_start();
    }
  header('location: login.php');
if($_SESSION['id-cus']==''){
}
$name    = $_POST['name'];
$address = $_POST['address'];

?>
<form action="3.php" method="POST">
	<table>
		<tr>
			<td>Name</td>
			<td><input type="text" name="name" value="<?php echo $name;?>"></td>
		</tr>
		<tr>
			<td>Address</td>
			<td><input type="text" name="address" value="<?php echo $address;?>"></td>
		</tr>
		<tr>
			<td></td>
			<td><button type="submit">Enter</button></td>
		</tr>
	</table>
</form>

page 3

 <?php
include 'libraries/config.php';
if(!isset($_SESSION))
    {
        session_start();
    }
if($_SESSION['id-cus']==''){
  header('location: login.php');
}
$name    = $_POST['name'];
$address = $_POST['address'];

?>
<?php echo $name;?>
<br>
<?php echo $address;?>