Codeigniter - Validar dos campos fecha

matches[other_date]

class MY_Form_validation {

    public function date_dif($date1, $date2){

		if ( ! isset($_POST[$date2]))

		{

			return FALSE;

		}

		$_date2 = $_POST[$date2];

                $date1  =date_create($date1);//"2013-03-15"

                $date2  =date_create($_date2);//"2013-12-12"

                $diff      =date_diff($date1,$date2);

                //if the result is + return TRUE else (-) FALSE

                return ( $diff->format("%R%a") > 0) ? TURE : FALSE;

	}

}

//ci2

$lang['date_dif']			= "The %s must be bigger than the %s.";//The first_date must be bigger than the second_date

//ci3

$lang['date_dif']			= "The %s must be bigger than the %s.";//The first_date must be bigger than the second_date

$lang['date_dif']		        = 'The {field} must be bigger than the {param}.";//The first_date must be bigger than the second_date

extends CI_Form_validation {

class MY_Form_validation extends CI_For_validation{