Fix Paypal payment API interaction with OSCommerce (Loaded Commerce) website

We have an ecommerce website built on osCommerce. Everything seems to be set up correctly, but when a payment is posted through Paypal, it does not register the payment with the website and we get a ton of "Paypal_Shopping_Cart_IPN" messages to our email, but no order notifications. There is obviously an error in receiving and processing the payment IPN from Paypal to complete the order. I need to have this fixed as soon as possible. The website is www.remembertheink.com. Winning provider will be chosen based on price, experience and successful completion of similar projects. OSCOMMERCE EXPERIENCE IS REQUIRED! Please do not bid if you do not have completed osCommerce projects in your portfolio. Must be able to communicate clearly in English. My budget is $50 or less for this project. I will ignore any bids above that. To prove that you have read the entire description of this project, please include the words "New Life" with your bid. Any bids without these words will be ignored.