Google checkout nightmare

Hi All, I'm trying to get a custom shopping cart integrated with Google Checkout. I've done it before with their older API, but it's changed a lot since I last used it. The official documentation is a mix and match of bits, and doesn't seem to follow any logical structure. The code samples Google gives only seem to work on a PHP4 system, and bring up countless errors on a PHP 5 system. Has anyone integrated this successfully before, or know of any decent PHP5 examples. I'm at my wits end, as I have to get this done today. So far my efforts go to the sandbox area and just say: Oops! Error time: 2010-05-26T14:54:24 (Coordinated Universal Time) (4878073251f78) We were unable to process your request. Which doesn't much help, as that value doesn't seem to be an error code (I get zero results when I Google it) Any help would be appreciated! Thanks, Ash http://www.ashleysheridan.co.uk