JPA Container many to many problem

General
1

I have problem on my application.
When I update its child data… it successfuly sent to database
But when I access its child data on an Entity Class…
The data doesn’t updated…
Also I made my connection with this code

[code]
public class AdminHomeView extends Panel implements View {

/**
 *
 */
private static final long serialVersionUID = 1L;

public static final String EDIT_ID = "dashboard-edit";
public static final String TITLE_ID = "dashboard-title";

private EntityManagerFactory emf = Persistence.createEntityManagerFactory(ApplicationUI.JPA);
private EntityManager em = emf.createEntityManager();

private Label titleLabel;
private CssLayout dashboardPanels;
private final VerticalLayout root;

[/code]and my Entities are made like this

[code]
@Entity
@Table(name = “users”)
public class Users implements Serializable {

/**
 *
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;

private String username;
private String password;

private boolean active;

@Temporal(TemporalType.TIMESTAMP)
private Date created_at;

@Temporal(TemporalType.TIMESTAMP)
private Date updated_at;

@ManyToOne
@JoinColumn(name = "level_id")
private User_level user_level;

@ManyToMany(targetEntity = System_queries.class)
private List<System_queries> systemQueriesSet;@Entity

@Table(name = “system_queries”)
public class System_queries implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;

@Column(name = "title")
private String title;
@Column(name = "description")
private String description;
@Column(name = "statement")
private String statement;

@Temporal(TemporalType.TIMESTAMP)
private Date created_at;
@Temporal(TemporalType.TIMESTAMP)
private Date updated_at;

@ManyToMany
@JoinTable(name = "users_system_queries",
        joinColumns={
                @JoinColumn(name = "systemQueriesSet_ID")
        },
        inverseJoinColumns={
                @JoinColumn(name = "Users_ID")
        })
private List<Users> userSet;

[/code]My theory is that the data should be updated because each time I change view the Page get Instantiaded again…
But why does the entity child wont be updated?