reCaptcha not working

my setting

k2 2.6.5 reCaptcha set "on"
joomla 2.5 reCaptcha set off

but at frontpage Register from reCaptcha box not show

Please make sure that captcha is enabled in user settings also, more details here >> http://www.gavick.com/documentation/general-questions/how-to-use-recaptcha/