Here my EJB

@Entity @Table(name = "modelos") @NamedQueries({ @NamedQuery(name = "Modelos.findAll", query = "SELECT m FROM Modelos m"), @NamedQuery(name = "Modelos.findById", query = "SELECT m FROM Modelos m WHERE m.id = :id"), @NamedQuery(name = "Modelos.findByDescripcion", query = "SELECT m FROM Modelos m WHERE m.descripcion = :descripcion")}) public class Modelos implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Basic(optional = false) @Column(name = "id") private Integer id; @Basic(optional = false) @Column(name = "descripcion") private String descripcion; @OneToMany(cascade = CascadeType.ALL, mappedBy = "idModelo") private Collection produtosCollection; @JoinColumn(name = "id_marca", referencedColumnName = "id") @ManyToOne(optional = false) private Marcas idMarca;

public Modelos() {
}

public Modelos(Integer id) {
    this.id = id;
}

public Modelos(Integer id, String descripcion) {
    this.id = id;
    this.descripcion = descripcion;
}

public Modelos(Integer id, Marcas idMarca) {
    this.id = id;
    this.idMarca = idMarca;
}

public Integer getId() {
    return id;
}

public void setId(Integer id) {
    this.id = id;
}

public String getDescripcion() {
    return descripcion;
}

public void setDescripcion(String descripcion) {
    this.descripcion = descripcion;
}

public Collection<Produtos> getProdutosCollection() {
    return produtosCollection;
}

public void setProdutosCollection(Collection<Produtos> produtosCollection) {
    this.produtosCollection = produtosCollection;
}

public Marcas getIdMarca() {
    return idMarca;
}

public void setIdMarca(Marcas idMarca) {
    this.idMarca = idMarca;
}

@Override
public int hashCode() {
    int hash = 0;
    hash += (id != null ? id.hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object object) {
    // TODO: Warning - this method won't work in the case the id fields are not set
    if (!(object instanceof Modelos)) {
        return false;
    }
    Modelos other = (Modelos) object;
    if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
        return false;
    }
    return true;
}

@Override
public String toString() {
    return "" + descripcion + "";
}

} And the method accesing from the Modelosfacade

public List findByMarcas(Marcas idMarca){ return em.createQuery("SELECT id, descripcion FROM Modelos WHERE idMarca = "+idMarca.getId()+"").getResultList(); } And the calling method from the controller

public String createByMarcas() {
    //recreateModel();
    items = new ListDataModel(ejbFacade.findByMarcas(current.getIdMarca()));
    updateCurrentItem();
    System.out.println(current.getIdMarca());
    return "List";
}

I do not understand why I keep falling in an EJB exception.