Im testing a little aplication in Java EE 6 with EJB 3.1 and JSF 2.0.
The question is that, when I call the Backing bean in JSF with a EL expression, and run the application, I get Exception because this backing bean is inaccesible and is null.

Here is my JSF code:
    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
        >
<h:head>
    <title>Insertar Usuarios</title>
</h:head>
<h:body>
    <h:form id="registro">
        <h:panelGrid columns="2">
            <h:outputText value="Username:"/>
            <h:inputText id="username" value="#{registro.usuario.user_Name}"/>
            <h:outputText value="Id:"/>
            <h:inputText id="id_user" value="#{registro.usuario.userId}"/>
            <h:outputText value="Mensaje:"/>
            <h:inputText id="mensaje" value="#{registro.usuario.userMessage}" required="true"/>
            <h:commandButton value="Crear usuario" action="#{registro.insertarUsuario()}" />
        </h:panelGrid>
        <h:messages/>
    </h:form>
</h:body>
</html>
Here is my Stateless EJB:
 @Stateless
public class NegocioImpl implements Negocio{
    @PersistenceContext(unitName = "manager1")
    private EntityManager em;
    @Override
    public void sayHelloFromServiceBean(User user) {
        User u = em.find(User.class, user.getUserId());
        if(u != null){
            System.out.println("Cuenta existente");
        }
        em.persist(user);
    }
    public String hola(){
        return "hola";
    }
}
And finally the backing bean:
    @Named
@RequestScoped
public class Registro {
    @Inject
    private Negocio negocio;
    private User usuario;
    public Registro(){
        usuario = new User();
    }
    public User getUsuario() {
        return usuario;
    }
    public void setUsuario(User usuario) {
        this.usuario = usuario;
    }
    public void insertarUsuario(){
        negocio.sayHelloFromServiceBean(usuario);
    }
    public void saluda(){
        negocio.hola();
    }
}
The project structure is make with Intellij IDEA.

Thanks in advance