Is the event itself OK? Can you trigger it with SWUE? Can you then see it in SWEL? (Is the event monitor on?).
Do you have the same key for you business object and change document. As far as I remember they need to be exactly the same (no leading zeros or anything).
How did you configure things in SWEC? Perhaps give us a screenshot? Have you defined the event for all the change document "scenarios" (both insert/update) - just to see/test if there is something wrong. For example I remember that certain SAP standard application created always an "update" change document - even when a new object was created (=insert).
Regards,
Karri