PayPal Instant Payment Notification confirmation (PHP)

I have no experience with Paypal's Instant Payment Notification system and I tried to create a PHP script to update site orders when an Instant Payment Notification is recieved. I need someone to look over the attatched script and to do the following: 1. Get the script to work. Currently I recieve no e-mail when an IPN is recieved, nor does the script update my database. 2. Re-write any code to make it more efficient. 3. Comment all new code so I know what it's doing. Attatched: [login to view URL] - The IPN script which needs fixing. [login to view URL] - and example of the information PayPal will send to the script. You must write 'I understand' in any comments or PM's to show you have read all of the above. If I do not see these words, your bid will be ignored.