Is this on a client or agaist the server? As i'm reasonably sure there isn't a capturable event for new documents as it's very multithreaded, and "Added" doesn't mean unlocked and checked in. Even on the client, each process connecting to worksite is seperate, so would need it's own event capture (I.e Desksite isn't nesaccerialy aware that a Word session has added a new document)
Whay you can do is frequently poll the Server for any documents added since the last time your process ran.