I've installed Scheduler on Moodle 1.9.10 and everything seems to work fine with two exceptions.
Issue #1 - students cannot drop their own appointments. I've verified that they have the disengage permission and they can see the link. However when the link is clicked the event remains.
Issue #2 - appointment details are not included in the notification. Users get notification emails but they are empty - there is no indication of when the appointment is. The email templates lead me to believe there should be more information.
Any ideas are appreciated.