Javascript validation doesn't work

[eluser]akho[/eluser]
here is my shoppingcart

Code:

<h1>Shopping Cart</h1>
<div id='pleft'>
&lt;?php echo form_open('shop/checkout'); ?&gt;
<table border='1' cellspacing='0' cellpadding='5'>
&lt;?php
        $TOTALPRICE = $_SESSION['totalprice'];
        if (count($_SESSION['cart'])){
        foreach ($_SESSION['cart'] as $PID => $row){
            $data = array(
                'name' => "li_id[$PID]",
                'value'=> $row['count'],
                'id' => "li_id_$PID",
                'size' => 5,
                'class' => 'process'
            );
            echo " <tr valign='top'> \n";
            echo " <td> ". form_input($data)." </td> \n";
            echo " <td id='li_name_".$PID."'> ". $row['name']." </td> \n";
            echo " <td id='li_price_".$PID."'> ". $row['price']." </td> \n";
            echo " <td id='li_total_".$PID."'> ".$row['price'] * $row['count']." </td> \n";
            echo "<td> <a href='#'>delete</a></td>\n";
            echo " </tr> \n";
        }
        $total_data = array('name' => 'total', 'id'=> 'total', 'value' => $TOTALPRICE);
        echo " <tr valign='top'> \n";
        echo " <td colspan='2'> &nbsp; </td> \n";
        echo " <td> $TOTALPRICE ".form_hidden($total_data)." </td> \n";
        echo " </tr> \n";
        echo "<tr valign='top'> \n";
        echo "<td colspan='2'> &nbsp; </td> \n";
        echo "<td> &lt;input type='button' name='update' value='update'&gt; </td> \n";
        echo "</tr> \n";
        echo " <tr valign='top'> \n";
        echo " <td colspan='2'> &nbsp; </td> \n";
        echo " <td> ".form_submit('submit', 'checkout')." </td> \n";
        echo " </tr> \n";
        }else{
            //just in case!
            echo " <tr> <td> No items to show here! </td> </tr> \n";
        }//end outer if count
?&gt;
</table>
&lt;/form&gt;
</div>
<div id='ajax_msg'> </div>