Thanks Helen,

>> if not IB_Transaction.InTransaction then <--- THIS MUST BE DONE

BEFORE THE PREPARE.

But, then the code sequence below is wrong?

with IB_Cursor do
begin
//*** here ib_transaction.started = false
Prepare;
//*** here ib_transaction.started = true

IB_Transaction.StartTransaction;
//... do something (Edit, Insert, ...)
IB_Transaction.Commit;

IB_Transaction.StartTransaction;
//... do something (Edit, Insert, ...)
IB_Transaction.Commit;

IB_Transaction.StartTransaction;
//... do something (Edit, Insert, ...)
IB_Transaction.Commit;

UnPrepare;
end;

Thanks,

Fábio.