IRP_MN_NOTIFY_CHANGE_DIRECTORY with FsRtl* package works in XP but not Vista

Hello list,

Sorry for this vague question but:

I’m having a weird problem with directory change notifications in my
filesystem. On XP, FsRtlNotifyChangeDirectory() notices my reports as
I would expect, but on Vista, I never receive any notifications–no
matter how many FsRtlFullReportChange()s are issued, they don’t seem
to be matched.

Does anybody know of something under the hood that could be causing a
difference between XP and Vista?