I have a problem with sending data to a table, 
the table is supposed to keep all placed order, cart_array, name, first name, last name, etc.. 
It submits, first time, and then if I want to place another order nothing happens... it won't send the data to the table.
If i delete the first entry from the table and place the order again, it works but the Auto Increment ID jumps from the one I just deleted(let's say from id-1 to id-14, depends on mow many attempts i've had)
the php block is
<?php
function register_transaction($register_order){
    array_walk($register_order, 'array_sanitize');
    $fields = '`' . implode('`, `', array_keys($register_order)) . '`';
    $data = '\'' . implode('\', \'', $register_order) . '\'';
    mysql_query("INSERT INTO `transactions` ($fields) VALUES ($data)"); 
}
if (empty($_POST) === false) {
            $register_order = array(
            'product_id_array' => $_POST['product_id_array'],
            'payer_email' => $_POST['payer_email'],
            'first_name' => $_POST['first_name']
                        );          
            register_transaction($register_order); 
        }
?>
form
<form action="" method="post">
    <ul style="position:relative">
        <li style="float:none;">Cart<br />
        <input type="text" name="product_id_array" value="<?php echo $product_id_array;?>" /></li>
        <li style="float:none;">Email<br />
        <input type="email" name="payer_email" value="<?php echo $user_data["email"];?>" /></li>
        <li style="float:none;">Name<br />
        <input type="text" name="first_name" value="<?php echo $user_data["name"];?>" /></li>
        <li style="float:none;">
        <input type="submit" value="Trimite Comanda" /></li>
    </ul>
</form> 
 
    