Fatal Error In CAPTCHA - my little forum

Fatal error: Call to a member function generate_code() on a non-object in includes/register.inc.php on line 248

Code is: $_SESSION['captcha_session'] = $captcha->generate_code();

Here are more details with code snippets:

Although you may think it's fixed, it isn't. I switched to the math thing for now. But I want captcha.