the announce interval is provided by the tracker, I believe.
Then you can override its value in vuze settings:
Tracker->Client.
It's set to 0 on mine, which is probably the default value indicating no override.
maybe that video helps.
then check Anon's 2nd post under the video.
On second thought, I don't think the interval is the issue here, GL should basically fetch a list of peers, dowload and report jack shit to the tracker.
so there is no next announce since GL blocks it.