MY_Form_validation doesn’t work

[eluser]crazytereza[/eluser]
I create "MY_Form_validation" library with additional rules. I wrote "MY_" like a prefix in config.php. And load "Form_validation" library in autoload.php.
As I know if you have prefix in config file then it’s being downloaded "MY_Form_validation" instead of "Form_validation" even if u load “Form_validation” in autoload.php.

Here is my constructor for MY_Form_validation:
function __construct() {
parent::CI_Form_validation();
$CI=&get;_instance();
$CI->lang->load('validation_new'); // Information about new mistakes-'validation_new'
echo "Constructor works!!!";
}

After checking I cant see "Constructor works!!!". So, it means constructor doesn’t work and the library “MY_Form_validation" with additional rules doesn’t work either. “Form_validation” library only works.

Maybe someone know where is a problem or the mistake.
Thanks.

P.S. Sorry if my English is bad. I posted it on the Russian codeigniter website but noone knows the answer.