validation and pass an id in url to view from controller

Hello
sorry for my bad english. i really need help 
i am creating a simple help desk and i have one question please answer me.

1: go to new ticket ( ex: localhost/helpdesk/index.php/ticket/show/10 ).

for number 1 i have a function ( public show ) and display all replies in id 10.

2: and show/10 has a form for reply your comment. ( screenshot : http://s6.uplod.ir/i/00880/op3jnntpy1lu.jpg )

then i need validation form when users submit new reply. i wrote validation rules, but i can't pass message error from controller to view (ticket/show/id).

PHP Code:

public function show()
    {
        $show = array();
        $id = $this->uri->segment('3');
        $groups_id = $this->ticket_model->get_groups_id($id);
        $show['show_ticket'] = $this->ticket_model->show($id, $groups_id);

        foreach ($show['show_ticket'] as $show_value){
            $show_gorup_id = $show_value['department_id'];
            $create_by_id = $show_value['user_id'];
        }

        $show['show_ticket_comment'] = $this->ticket_model->get_reply($id);

        foreach ($this->aauth->get_user_groups() as $user_groups) {
            $user_groups_id = $user_groups->id;
        }

        if (($this->aauth->is_member('Admin')) ||($user_groups_id == $show_gorup_id) || ($create_by_id == $this->aauth->get_user_id())) {
            $this->template->load('ticket/show_ticket', $show);
        }else{
            echo 'Access Denied';
        }
    } 


PHP Code:

  public function reply()
    {
        $this->form_validation->set_rules('comment','Comment','required|trim');
        if($this->form_validation->run() == FALSE){
            $ticket_id = $this->input->post('ticket_id');
            //$show['show_ticket_comment'] = $this->ticket_model->get_reply($ticket_id);
           // $this->template->load('ticket/show/'.$ticket_id,array('errors' => validation_errors('','<br />')));
           // return;
            
            // what code needs here ??????

        }else{
            if($_FILES['userfile']){
                $this->load->library('upload', $config);
                //$this->upload->initialize($config);
                if($this->upload->do_upload('userfile')){
                    $config['upload_path'] = './file_ticket';
                    $config['allowed_types'] = 'gif|jpg|png|jpeg|pdf|doc|docx|txt';
                    $config['max_size'] = 4000;
                    $config['max_width'] = 11024;
                    $config['max_height'] = 7168;
                    $upload_data = $this->upload->data();
                    $file_name = $upload_data['file_name'];

                    $reply_ticket['ticket_comment_id'] = '';
                    $reply_ticket['ticket_id'] = $this->input->post('ticket_id');
                    $reply_ticket['user_id'] = $this->aauth->get_user_id();
                    $reply_ticket['comment'] = $this->input->post('comment');
                    $reply_ticket['create_date'] = now();
                    $reply_ticket['file'] = $file_name;
                    $insert_ticket_comment = $this->ticket_model->reply($reply_ticket);
                    if ($insert_ticket_comment){
                        $show = array();
                        $id = $this->input->post('ticket_id');
                        $groups_id = $this->ticket_model->get_groups_id($id);
                        $show['show_ticket'] = $this->ticket_model->show($id, $groups_id);

                        redirect('ticket/show/'.$id);
                    }
                }else{
          //          $error = array('error' => $this->upload->display_errors());
echo '11';
            //        $this->load->view('show_ticket', $error);
                }
            }else{print_r($_POST);}
        }
    }