How do I implement human verification on my custom page

[veenuisthebest]

Hii..

I was looking for how to implement vB's default human verification on my custom page.
Then I found this in one of the pages of vB.

PHP Code:

require_once(DIR . '/includes/class_humanverify.php');
        $verify =& vB_HumanVerify::fetch_library($vbulletin);
        $human_verify = $verify->output_token(); 
if (!$verify->verify_token($vbulletin->GPC['humanverify']))
{
standard_error(fetch_error($verify->fetch_error()));
} 


and then simply adding $human_verify at the desired location in the template. This works just perfect BUT even the correct entered captcha is giving error saying "Incorrect String entered."

There must be some minor mistake I am making.. any help is much appreciated !!