By case, do you have rows in SessForm with the FK defined to the parent group ?
In you example it would be : "Administrator MISS - Module" defined in the Formation FK of any row of the SessForm Table.
Yes of course, I have 1 or more session date for each Formation.
Does it work if you use a text or a number instead of a date in the base FK to display ?
YES, it works if I change the Field type from
Calendar to
String.
Result :
The combo is fully populated when the field type is String, but not if the field type is DateTime.
But the DateTime SHOULD work anyway.
Are you sure of your tests ?
Yes I am