Problem with repeating Calendar Events

tion:
We have a repeated calendar appointment in the users Mailfile.
The user changes the time for a single instance of the appointments and
we need to fetch the new values after the series is changed.
I.e. original times:
01.02.2017 10:00:00;02.02.2017 10:00:00;03.02.2017 10:00:00;04.02.2017 10:00:00
The user changes now the second entry in the calendar from 10:00 to 11:00
I need to retrieve the new values for the series.

Problem:
When saving the document, the Parentdocument of the series is updated (we get that through “ApptUNID”).
I try to fetch the new values from the Parentdocument with LotusScript through Item “RepeatDates”, but
this document still gives me the old values…
I tried to fetch the values from QuerySave, PostSave and Queryclose, but all
with the old values.
Tried also an Evaluate on the document, same (wrong) result.

Tried with Notes 8.5.3 FP5 and 9.0.1 (will post this in both forums)

Any idea what is wrong?
Best regards
Joerg