Ho to control if a table is updated from another user in a multiuser environment

Hi all,

I'm not able to control if a table is updated from another user in a
multiuser environment.

Consider this situation :

To perform a secure update to some tables i use a tIbTransaction compenent
with those poperties :
    nowait
    write
    consistency
    lock_write=TABLE1
    lock_write=TABLE2
    lock_write=TABLE3
    protected

From station 1 i open a form where with a Tibdataset compent i activate an
edit event to the TABLE1 (the transaction parameters are: read_committed,
rec_version, nowait);

From station 2 i activate the update to the tables with the previous
transaction that lock the table1, 2 and 3;

From station 1 after the end of the update executed from the station 2 i
post the changes to a record that is been changed from the station 2;

From the station 2 i'm not able to know that the table or the record is been
updated from another user.

Thanks in advance for all the answer.

Massimo.