form_validation->run() not working as expected

[eluser]Unknown[/eluser]
It was the set_rules() invocation that caused the problem. That may have come from following an older tutorial or user guide. Everything's working properly now. The offending code now looks like this:

Code:

// set validation rules
    $rules = array(
        array('field' => 'first_name',
              'label' => 'First Name',
              'rules' => 'required|min_length[2]|max_length[20]') ,
        array('field' => 'last_name',
              'label' => 'Last Name',
              'rules' => 'required|min_length[2]|max_length[20]')
      ) ;

    $this->form_validation->set_rules($rules);

Thanks for your help!