EJB, EntityManager and merging problems

Hello,

I've been looking for nice database I/O way and I've decided to use
(suggested by NetBeans) the EJB.

In fact, I was looking for something, which would speed up my work,
unfortunately I'm stuck for last 4 hours with annoying update database
problem.

Fetching data from database works perfectly. BUT, when I'm trying to
update records, I no changes are made in the database. I wish you'll
help me finding the reason.

As it has been described in many, many google-found pages, I've build an
object, which I use as entity manager. Sample:

@Stateless
@TransactionManagement(TransactionManagementType.CONTAINER)
public class UserManager {

     @PersistenceContext(unitName="MyDbPU")
     private EntityManager em;
     @Resource
     SessionContext context;
     @EJB
     private CupUserFacade userFacade; // Dunno whether it's required?

     public int UpdateUser() {
         EntityManagerFactory emf =
        Persistence.createEntityManagerFactory("MyDbPU");

         em = emf.createEntityManager();
         CupUser user = (CupUser) em.find(CupUser.class, 2);
    user.setName("fonk you");
         try {
             CupUser upUser = em.merge(user);
             System.err.println(upUser.getName());
             em.close();

             return 1;
         } catch (Exception ex) {
             System.err.println(
        "UserManager.UpdateUser(): "
            + ex.getMessage());
             return 0;

         }
     }

     @PersistenceContext
     public void setEntityManager(EntityManager eman) {
         this.em = eman;
     }
}

The log file sayz:

FINEST: Execute query ReadObjectQuery(referenceClass=CupUser sql="SELECT
.... FROM cup_user WHERE (ID = ?)")
SEVERE: fonk you
FINEST: Merge clone with references entity.CupUser[id=2]
SEVERE: true // is open() EntityManager
FINER: release unit of work

In fact it does not say anything about updating queries...
That's annoying, because I really don't know what am I doing wrong.

Please help. Thank you very much.

Przemek M. Zawada