[paypal integration with custom site]

Hello, I am looking for an experienced PHP + paypal developer. I have created a form based paypal page but It don't work. (I can see 'Dispatch Error, please check logfile for more information' in the paypal page) The requirements: 1) Development or fix with checking the prototype site. Your updates should work with the custom site. I will prepare the server side environment for you. You can develop with the environment. 2) The paypal page will deposit money like GAF. 3) IPN page is also under construction. The basic files are included but not testing yet. Please ensure to work. 4) Testing with sandbox by you is required. Testing including IPN. 5) Ensuring transaction between the site and sandbox is the task. [site] -> [sandbox] (Posting data features through Website Payments Standard exist but some fixing is required.) [site] <- [sandbox] (Testing the logging feature is required. Logging functions are already exist. Testing is required.) You don't need to implement DB related tasks. Ensuring the transaction is the project. Thank you.