Registration with CodeIgniter Ion Auth

问题

I am trying to register a user with Ion Auth, but the register() function does not seem to report any error messages. How does one register with Ion Auth? I've already read various tutorials like this one and this one (and the documentation), but they do not seem to be working.

function register()
{
    // do not allow registration if logged in
    if ($this->ion_auth->logged_in())
    {
        redirect('/');
    }

    $this->load->helper(array('form', 'url'));
    $this->load->library('form_validation');

    $this->form_validation->set_rules('name', 'Name', 'trim|required|xss_clean');
    $this->form_validation->set_rules('email', 'Email', 'trim|required|valid_email|callback_email_check');
    $this->form_validation->set_rules('email2', 'Email Confirmation', 'trim|required|valid_email|matches[email]');
    $this->form_validation->set_rules('password', 'Password', 'trim|required|md5');

    if ($this->form_validation->run() == FALSE)
    {
        $this->data['message'] = (validation_errors()) ? validation_errors() : $this->session->flashdata('message');

        $this->load->view('header');
        $this->load->view('register', $this->data);
        $this->load->view('footer');
    }
    else
    {
        $username = $this->input->post('email');
        $password = $this->input->post('password');
        $email = $username;

        $additional_data = array(
            'first_name' => $this->input->post('name'),
            'last_name' => '',
        );

        if (!$this->ion_auth->email_check($email))
        {
            $group_name = 'users';
            $uId = $this->ion_auth->register($username, $password, $email, $additional_data, $group_name);

            if ($uId == FALSE)
            {
                $this->session->set_flashdata('message', $this->ion_auth->errors());
                redirect("home/register", 'refresh');
            }
            else
            {
                redirect('/'); // registration success
            }
        }
    }
}

function email_check($str)
{
    if ($this->ion_auth->email_check($str))
    {
        $this->form_validation->set_message('email_check', 'This email is already registered.');
        return FALSE;
    }

    return TRUE;
}

来源：https://stackoverflow.com/questions/20938227/registration-with-codeigniter-ion-auth