Help with Registering objects/access cache

Question

Below is the save routine i use to persist my top-level objects to the database.
It seems very likely that I am doing something fundamentally wrong as I am obvserving behaviour that I do not expect.
For example, I am using a field called version_id to hold an integer for optimistic locking. The first time I save the object, the correct sql is created, and the database row looks as I would expect. However, subsequent attempts to save do not work because I cannot figure out how to get a reference to the object with the incremented version_id.
It would be much appreciated if someone can see things i am doing incorrecty with the implementation i have included below.
thanks in advance.
craig
public static Object save(IdentifiableValue obj, String sessionName) {
          Object entity= null;
          try {
               UnitOfWork uow= getSession(sessionName).acquireUnitOfWork();
               if (obj.isNew())
                    uow.registerObject(obj);
               entity= uow.deepMergeClone(obj);
               //                    uow.printRegisteredObjects();
               uow.commit();
               //               uow.registerObject(facility);
          } catch (DatabaseException e) {
               e.printStackTrace();
          Object returnValue= getSession(sessionName).readObject(obj);
          return returnValue;
     }

Answer 1

When I create a new record, the id (sequence generated) gets set fine, but not the version number.
When I save a record, the version id is not incremented.
It seems to use the version number field properly in the sql though.
Below is my sessions.xml entry, which looks like I am not JTS unless I am doing something incorrect.
Any help is much appreciated.
<session>
          <name>default</name>
          <project-xml>toplink.xml</project-xml>
          <session-type>
               <server-session/>
          </session-type>
          <enable-logging>true</enable-logging>
          <logging-options>
               <log-debug>true</log-debug>
               <log-exceptions>true</log-exceptions>
               <log-exception-stacktrace>true</log-exception-stacktrace>
               <print-thread>true</print-thread>
               <print-session>true</print-session>
               <print-connection>true</print-connection>
               <print-date>true</print-date>
          </logging-options>
          <login>
          <platform-class>oracle.toplink.internal.databaseaccess.OraclePlatform</platform-class>
               <datasource>jdbc/toplinkDS</datasource>
               <uses-external-connection-pool>true</uses-external-connection-pool>
               <uses-external-transaction-controller>false</uses-external-transaction-controller>
          </login>
     </session>