This is probably an elementary misunderstanding on my part.

I am converting a VCL BDE app to Firebird.
All old controls have been converted appropriately in accordance with
the guidance notes.

I have added a TIBOTransaction and set it as the default transaction
for the TIBODatabase which has taken the place of the BDE database.
(It is my understanding this will ensure all transactions by a single
user will be kept together)

Without fully understanding why, I have also added a TIB_Session and
referenced it from the TIBODatabase.

I have set AutoCommit to true in the TIBOTransaction and the
TIBODatabase.

When testing data entry or edit, using the existing TNavBar controls,
changes get posted but not committed. Even exiting the app does not
commit any updates.

Isolation is tiCommitted.

Any clues as to what I have missed?

Thanks in advance

George