Have you compared the dates? If an event is too old it won't appear in the Events module. Check the database tables to see if the data is in there. Also make sure you have the latest Web Service module installed.
A new version of this module is in design now. However, it won't work with the current DNN Events module, it will have it's own Events module. The primary reason for this is so that new releases of the DNN core Events module won't break the OnyakTech Events module, which is what you see now. Also, without being able to change the core Events module myself, most of the new feature requests won't be able to get added.
So, there will soon be a new version of the OnyakTech Events module. There are a few "Power Users" involved with this and I expect easy integration with some of the other modules. Development won't start on this until early 2009 due to current BETA releases of Axon, Soma Elite integration with Axon, H2O 4.0 and SigmaPro 8.0. As well as a new server layer component that will add some really nice features to all modules, not just OnyakTech's.
Also...there is a 30 day refund policy. If you don't like the way the old Events add-in works, it's not a loss since you can request a full refund.