problems sending info to / from sessions

Hi everyone.
I've been using php/mysql for about a year now and have learnt a huge
amount. I've re-designed my whole website to use includes and databases but
I'm having a real problem with the shop.

The shop is powered by world pay and works by sending information to their
website using a form.
My problem is that my shopping cart system that i use (OsCommerce) doesn't
seem to be able to send this information to world pay, though it displays
this item on this page: http://magic2k.com/catalog/checkout_confirmation.php

There must be some kind of break down of communications between thiis page
and the worldpay page. I'm getting desperate to sort this out and was
wondering if anyone here could help.

Many thanks in advance.

--
Neil Trigger
Magic2k Webmaster
http://www.magic2k.com
http://www.magic2k.co.uk