Gastenboek werkt niet

<form action="index.php?link=gastenboek.php" method="post" >
	<br><table width="90%" border="0" cellspacing="0" cellpadding="3" align="center">
					<tr>
						<td class="nieuwshoofd" bgcolor="#33CC00">
						<strong class="menutxthead">Geschreven door <input value="Typ hier uw naam" type="text" name="door"></strong>
						<span class="menutxthead"> | <?php echo date("d-m-Y H:i:s", time()); ?></span>
						</td>
					</tr>
					<tr>
						<td class="nieuwsinhoud">
						<textarea name="bericht" rows="8" cols="50">Typ hier uw bericht!</textarea><br>
						<input type="submit" value="Bericht plaatsen!">
						</td>
					</tr>
				</table>
<?php 
mysql_connect("localhost",USER,WACHTWOORD);     
mysql_select_db(DATABASE);

$query = "SELECT * FROM gastenboek ORDER BY id DESC"; 
$sql=mysql_query($query) or die (mysql_error());
 
while ($obj=mysql_fetch_object($sql)) { 
	$door = $obj->door;
	$datum = $obj->datum;
	$bericht = $obj->bericht;
	?>
	
	<br><table width="90%" border="0" cellspacing="0" cellpadding="3" align="center">
					<tr>
						<td class="nieuwshoofd" bgcolor="#33CC00">
						<strong class="menutxthead">Geschreven door<?php echo $door; ?></strong>
						<span class="menutxthead"> | <?php echo $datum ?></span>
						</td>
					</tr>
					<tr>
						<td class="nieuwsinhoud">
						<?php echo $bericht; ?>
						</td>
					</tr>
				</table>
				
<?php }

if(isset($_POST['door']) and isset($_POST['bericht']) and $_POST['door']!='Typ hier uw naam' and $_POST['bericht']!='Typ hier uw bericht!' ) {
	$bericht = $_POST['bericht'];
	$door = $_POST['door'];
	$datum =  date("d-m-Y H:i:s", time());
	
	$bericht = str_replace("\n", "<br>", $bericht);
	
	$query = "INSERT INTO gastenboek(bericht, door , datum) VALUES ('$bericht', '$door', '$datum')"; 
  	$sql=mysql_query($query) or die (mysql_error());
}
?>

<form action="index.php?link=gastenboek.php" method="post" >
	<br><table width="90%" border="0" cellspacing="0" cellpadding="3" align="center">
					<tr>
						<td class="nieuwshoofd" bgcolor="#33CC00">
						<strong class="menutxthead">Geschreven door <input value="Typ hier uw naam" type="text" name="door"></strong>
						<span class="menutxthead"> | <?php echo date("d-m-Y H:i:s", time()); ?></span>
						</td>
					</tr>
					<tr>
						<td class="nieuwsinhoud">
						<textarea name="bericht" rows="8" cols="50">Typ hier uw bericht!</textarea><br>
						<input type="submit" value="Bericht plaatsen!">
						</td>
					</tr>
				</table>
<?php 
mysql_connect("localhost",USER,WACHTWOORD);     
mysql_select_db(DATABASE);
 
$query = "SELECT * FROM gastenboek ORDER BY id DESC"; 
$sql=mysql_query($query) or die (mysql_error());
 
while ($obj=mysql_fetch_object($sql)) { 
	$door = $obj->door;
	$datum = $obj->datum;
	$bericht = $obj->bericht;
	?>
 
	<br><table width="90%" border="0" cellspacing="0" cellpadding="3" align="center">
					<tr>
						<td class="nieuwshoofd" bgcolor="#33CC00">
						<strong class="menutxthead">Geschreven door<?php echo $door; ?></strong>
						<span class="menutxthead"> | <?php echo $datum ?></span>
						</td>
					</tr>
					<tr>
						<td class="nieuwsinhoud">
						<?php echo $bericht; ?>
						</td>
					</tr>
				</table>
 
<?php }
 
if(isset($_POST['door']) and isset($_POST['bericht']) and $_POST['door']!='Typ hier uw naam' and $_POST['bericht']!='Typ hier uw bericht!' ) {
	$bericht = $_POST['bericht'];
	$door = $_POST['door'];
	$datum =  date("d-m-Y H:i:s", time());
 
	$bericht = str_replace("\n", "<br>", $bericht);
 
	$query = "INSERT INTO gastenboek(bericht, door , datum) VALUES ('$bericht', '$door', '$datum')"; 
  	$sql=mysql_query($query) or die (mysql_error());
}
?>