Upload form validation call back error Codeigniter HMVC - php

Question

i have function where i want to upload data and have its upload errors validated.. but the problem is i got this error Unable to access an error message corresponding to your field name Document.
public function register(){
$this->load->library('form_validation');
$this->form_validation->set_rules('DOC_NAME', 'Document Name' ,'trim|required');
$this->form_validation->set_rules('DOC_TYPE', 'Document Type' ,'trim|required');
$this->form_validation->set_rules('DOC_DATE', 'Date' ,'trim|required');
$this->form_validation->set_rules('userfile', 'Document', 'callback_pdf_upload');
if($this->form_validation->run($this) == TRUE){
echo "Account Created Successfully";
}else{
$this->add_view();
}
}
function pdf_upload(){
if($_FILES['userfile']['size'] != 0){
$upload_dir = './uploads/pdf';
if (!is_dir($upload_dir)) {
mkdir($upload_dir);
}
$config['upload_path'] = $upload_dir;
$config['allowed_types'] = 'pdf';
//$config['file_name'] = 'userimage_'.substr(md5(rand()),0,7);
//$config['overwrite'] = false;
$config['max_size'] = '5120';
$this->load->library('upload', $config);
if (!$this->upload->do_upload('userfile')){
$this->form_validation->set_message('userfile', $this->upload->display_errors());
return false;
}
else{
$this->upload_data['userfile'] = $this->upload->data();
return true;
}
}
else{
$this->form_validation->set_message('userfile', "No file selected");
return false;
}
}
i am well aware of the callback issues of HMVC on code igniter and already have the MY_Form_validation library. what is the error of this ? i also got the error ERROR - 2016-07-15 15:47:35 --> Could not find the language line "form_validation_pdf_upload" on my error logs.

Answer 1

Change this :
$this->form_validation->set_message('pdf_upload', $this->upload->display_errors());