When first going into book a service activity (unbooked), the scheduled date/time becomes the start/end of the search filter, and then when you click to book, the booking form comes up with the correct date and times for start/end (takes the duration into account).. If you later need to add a resource to the Service Activity, then the start/dates and time on the booking form on does not match what the scheduled date/time is on the Service Activity, and it disregards the duration. When you change the start time to be what it should be, it changes the end date/ time to the same value -without the duration. If the start time changes, the end time should move in step accordingly with the duration. That is a bit flakey even on unbooked.. Moving the scheduled time forward, does move the end time - but moving the time earlier does not move the end time..