I don't know if you're interested.
All DataSet and ItemSource are active.
Setting: TDBMultiMonthSource.NumberOfMonth > 1

If I switch from TDBHalfDayPeriodSource or TDBMonthSource to TDBMultiMonthSource, I get an error "Invalid argument to date encode".
This only happens on the first call !!!
I solved this by very thoroughly setting the DataSet and ItemSource Active to False.
Yours sincerely.