Oscommerce guru needed to fix a bug

Project Description:
Hi,
Please only bid if you are a crack on Oscommerce and can find out and correct the following bug:

I have an oscommerce 2.2 ms2 shop.

Everything works well except a promo code that i have inserted in /includes/modules/order_total/ot_promo_code.php

when i try to buy something and enter a promo code i should get a discounted price of 20% wich don't work anymore.

The thing is that, on checkout_confirmation.php the discounted price isn't shown anymore, neither on the paypal page etc.

While if i enter an affiliate code, it works, i see the discount and discounted price on checkout_confirmation.php


If you are very familiar with this oscommerce version and can figure out and correct that bug, bid on my project and send me a pm!

I will award the project very soon.

thanks