The Event Manager is an area of the CMS Made Simple admin area that new users often find confusing. New users sometimes get the impression that Events and UDTs are completely modular and can just be plugged together willy-nilly and it will somehow work. Even when users are aware that each event transmits a different set of parameters, it's not always clear to them what those parameters are.
This recipe gives some pointers for identifying event parameters and their data structures. To fully utilize this recipe, you'll need read access to your server's PHP error logs.