Callback Not Working Need Help

[eluser]razerone[/eluser]
Hi I my call back function is not working have not idea why?

Code:

public function login_validation() {
  $this->load->library('form_validation');
  $this->form_validation->set_rules('email', 'Email', 'trim|required|callback_validate_credentials|xss_clean');
  $this->form_validation->set_rules('password', 'Password', 'required|md5');

  if ($this->form_validation->run())
  {
   redirect('users/members');
  }
  else
  {
   $this->load->view('login');
  }
}

public function validate_credentials() {
  $this->load->model('model_users');

  if ($this->model_users->can_log_in()) {
   return true;
  } else {
   $this->form_validation->set_message('validate_credentials', 'Incorrect Username/Password.');
   return false;
  }
}

I have now found out problem issue it is with HMVC I have found a link that helps if any one has hmvc and has problems will call back

How to make Call back works with HMVC