Updaten met checkbox werkt niet

<?php
$host="localhost"; // Host name
$username="*****"; // Mysql username
$password="*****"; // Mysql password
$db_name="*****"; // Database name


// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");

$sql="SELECT supplies.*, jss_products.name as name, inkoop.*  FROM inkoop inner join supplies on inkoop.oemcode = supplies.oemcode inner join jss_products on supplies.oemcode = jss_products.suppliercode where besteld = '0'";
$result=mysql_query($sql);

$count=mysql_num_rows($result);

?>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><style type="text/css">
<!--
body,td,th {
	font-family: Verdana, Arial, Helvetica, sans-serif;
	font-size: 12px;
}
-->
</style><table width="100%" border="0" cellspacing="1" cellpadding="0">
<tr>
<td><form name="form1" method="post" action="">
<table width="100%" border="0" cellpadding="3" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<td bgcolor="#FFFFFF">&nbsp;</td>
<td colspan="14" bgcolor="#FFFFFF"><strong>Bestellingen </strong></td>
</tr>
<tr>
<td align="center" bgcolor="#FFFFFF"><input type="checkbox" onClick="Checkall(this.form);" /><strong>Alles</strong><br /></td>
<td align="center" bgcolor="#FFFFFF"><strong>Datum</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Aantal</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Oemcode</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Omschrijving</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Klant</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Filiaal</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Verkoper</strong></td>

</tr>
<?php

while($rows=mysql_fetch_array($result)){
?>
<tr>
<td align="center" bgcolor="#FFFFFF"><input name="item" type="checkbox" id="item" value="<? echo $rows['ID']; ?>"></td>
<td bgcolor="#FFFFFF"><? echo $rows['datum'];?></td>
<td bgcolor="#FFFFFF"><? echo $rows['aantal']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['oemcode']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['name']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['klant']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['filiaal']; ?></td>
<td bgcolor="#FFFFFF"><? echo $rows['verkoper']; ?></td>



</tr>
<?php
}
?>
<tr>
<td colspan="14" align="center" bgcolor="#FFFFFF"><INPUT TYPE="button" VALUE="Bestelling printen" onClick="printPage()"></td>
</tr>
<tr>
<td colspan="14" align="center" bgcolor="#FFFFFF"><input name="update" type="submit" id="update" value="Bestelling verwerken"></td>
</tr>
<?
// Check if update button active, start this

if (isset($update)) {
$item = $_POST['item'];
for($i=0;$i<$count;$i++){
$del_id = $item[$i];
$sql = "UPDATE supplies set besteld='1' WHERE ID='$del_id'";
$result = mysql_query($sql);
}

// if successful redirect to bestel.php
if($result){
echo "<meta http-equiv=\"refresh\" content=\"0;URL=bestel.php\">";
}
}
mysql_close();
?>
</table>
</form>
</td>
</tr>
</table>