Form Validation Callbacks in HMVC in Codeigniter problem

create a file name MY_Form_validation.php and put it in the application/libraries folder

< ?php if (!defined('BASEPATH')) exit('No direct script access allowed');

class MY_Form_validation extends CI_Form_validation
{
 function run($module = '', $group = '') {
 (is_object($module)) AND $this->CI =& $module;
 return parent::run($group);
 }
}
/* End of file MY_Form_validation.php */
/* Location: ./application/libraries/MY_Form_validation.php */  

when using validation, put $this into the $this->form_validation->run()
example

if($this->form_validation->run($this)) {
//your code down there 
}