This is a migration from 1.3.9h to 1.5. I already had custom field for invoices in version 1.3.9h, but now when migrating Zencart it doesn't display the Custom field for the column created on table customers as customers_dni

So I edited admin/invoice.php and added this:

<td class="main"><?php echo '<b>' . ENTRY_DNI . "</b>&nbsp;" . $order->customer['customers_dni']; ?></td>

besides in includes/languages/english & spanish i edited invoice.php and added this:

define('ENTRY_DNI', 'DNI:');

So far what I am able to print is "DNI:" but there is no value printed for the that value which is on the DB.

What am I missing. Thanks in advance.