How to work with TIL?

[Chaosworld]

Hi,
I am using the most new revision 187 of Zeos 6.6 with Delphi 5. I have only problems with the TransantIsolationLevel. I was starting with tiReadCommitted and went up to tiSerializable. I am using MySQL 4.1 but i also tried MySQL 5.0.
The point is, that I want, that if someone in the network is editing a row in a table nobody else should be able to edit this row. But it does not work, all can edit the same row. I also tried to work with:
Connection.StartTransaction;
and
Connection.Commit;
But still several people can change the same row in the same time, with the known problems of lostupdate.
So what i am doing wrong?

Thanks for every replay

PS: Oh i am using Protocol: mysql-4.1 (or mysql-5.0). When i try to use mysqld-4.1 or mysqld-5.0 I get a crash of the dll (access-error). Of MySQL I use mysqld and InnoDB so that the Database should be able to use Transactions.