Problem, add new records in a many-to-many relation

[babak behzadi]

Hi,
I have two entities 'Person' and 'Team' which are mapped by a bidirectional many-to-many relation using annotations, as follow:

@Entity
public class Perosn implements Serializable {
      ....
      private Collection<Team> teams;
      ....

     @ManyToMany(cascade = {javax.persistence.CascadeType.PERSIST, javax.persistence.CascadeType.MERGE})
     @JoinTable(name = "person_team",
            joinColumns = { @JoinColumn(name = "person_id")},
            inverseJoinColumns = {@JoinColumn(name = "team_id")})
     public Collection<Team> getTeams() {
        return advisers;
     }
}

,

@Entity
public class Team implements Serializable {
      ....
      private Collection<Person> persons;
      ....

     @ManyToMany(mappedBy = "teams",
            cascade = {javax.persistence.CascadeType.PERSIST, javax.persistence.CascadeType.MERGE})
     public Collection<Person> getPersons() {
        return persons;
     }
}

my service class{1, 2: According to 'Christian Bauer and Gavin King, Java Persistence with Hibernate by Manning Publication Co. Page 301, P 2'}:

@Service("teamService")
public class TeamService extends DataAccess {
    ....
    public void addTeamToPerson(String teamId, String personId) {

        Team team= getTeam(teamId);
        Person person= personService.getPerson(personId);
        //1.
        person.getTeaMs().add(team);
        //2.
        team.getPersons().add(person);
        super.update(team);
        super.update(person);
    }
    ....
}

public abstract class DataAccess<E> {

    private EntityManager manager;
    ....
    public void update(E object) {
        try {
            manager.getTransaction().begin();
            manager.merge(object);
            manager.getTransaction().commit();
        } catch (Exception e) {
            ....
        }
   }
   ....
}

And my problem: Calling method 'addTeamToPerson()' does not cause to add a new record to join table 'person_team'!!!
Note: I traced the code line by line, there's no error or exception and the transaction commits.
Please help me solve it.

regards.
babak behzadi