Hidden field not been submitted with form validation

I have a small issue.

I am now using form helper and form validation to submit my up and down votes.

But for some reason using the form validation on the down_vote does not submit it keeps on returning false.

I am not sure why form validation does not work with hidden fields.

The var dump is working. form helper is auto loaded.

Code:

array (size=1)
 'down_vote' => string '1' (length=1)

Controller Forum

PHP Code:

<?php

class Forum extends CI_Controller {

    public function __construct() {
        parent::__construct();
        $this->load->model('model_forum');
        $this->load->library('form_validation');
    }

    public function index() {
        $data['forum_user_total_votes'] = 'Your Rep ' .  $this->model_forum->get_forum_user_reputation();
        $data['total_votes'] = $this->model_forum->get_forum_question_reputation();

        $this->load->view('common/header');
        $this->load->view('forum/forum_question_demo', $data);
        $this->load->view('common/footer');
    }

    public function down_vote() {
        

        $this->form_validation->set_rules('down_vote', 'Down Vote');

        if ($this->form_validation->run() == FALSE) {

            echo "Does Not Work";

            var_dump($_POST);

            //redirect('forum');

        } else {

            echo $this->input->post('down_vote');

            $this->model_forum->update_forum_question_down_vote();
            $this->model_forum->update_forum_user_reputation_down_vote();
                
            redirect('forum');
        }
    }
} 


View

PHP Code:

<div class="col-lg-3 col-md-3 col-sm-3 col-xs-12 text-center">
<div class="well">

<?php echo form_open_multipart('forum/up_vote');?>
<?php echo form_hidden('up_vote', '1');?>
<button type="submit" style="background-color: transparent; border: none;"><i class="fa fa-angle-up fa-4x"></i></button>
<?php echo form_close();?>

<div class="total"><?php echo $total_votes;?></div>

<?php echo form_open_multipart('forum/down_vote');?>
<?php echo form_hidden('down_vote', '1');?>
<button type="submit" style="background-color: transparent; border: none;"><i  class="fa fa-angle-down fa-4x"></i></button>
<?php echo form_close();?>

</div>
</div> 


There's only one rule - please don't tell anyone to go and read the manual.  Sometimes the manual just SUCKS!