reCAPTCHA helper and validation function (easy-to-use captcha)

[eluser]Unknown[/eluser]
I followed your instruction as you said,
But i got problem..
"
Call to undefined method CI_Form_validation::CI_Form_validation() in C:\xampp\htdocs\zippyaccount\system\libraries

\MY_Form_validation.php on line 6"

where i use "class MY_Form_validation extends CI_Form_validation {

function MY_Form_validation() {
parent::CI_Form_validation();
}"

Actually i am using codeigniter 2.1.2.

Please help me...