Concurrency Issue -- Transaction Serialization

[SAMINATHAN]

Hi         I  am trying to stop the concurrent access of my entity bean.Let me  first give  the brief   We are using SQL Server 2000,Jonas 2.2.6 App Server and Swing Client.   We have a form that contains basically three button New , Modify and View .We will call the entity bean via session facade for the each operation.For New, ejbCreate() of entity will be called, modify -- ejbLoad() and ejbStore() will be called.   All are BMP beans and trasaction is Container Manged.   Now  i have set in my Data access object 's update method                   Connection con = util.getConnection();                 Debug.println("**************$$$$$$$$$$$$$$$$$$$$$$$$****************");                 dbConnection.setTransactionIsolation(4);                 int iIsolationLevel2 = dbConnection.getTransactionIsolation();                 Debug.println("update Isolation Level-- AFTER SETTING   : "+iIsolationLevel2);     Here is the problem, i have set the isolation level -- 4 (TRANSACTION_SERIALIZABLE) and try to modify the same record simultaneously and it is happening.   I don't understand why it is not throwing the sql exception?   Can any one help me??   Thanks and Regards Saminathan.