Recaptcha not showing captchas any more

Hello,today the captchas on our page are not working any more. I'm always getting an empty box without images. Please see attachment.What's wrong with that? We didn't change anything in our code.Best regards,Stefan -- You received this message because you are subscribed to the Google Groups "reCAPTCHA" group. To unsubscribe from this group and stop receiving emails from it, send an email to recaptcha+unsubscribe@googlegroups.com. To post to this group, send email to recaptcha@googlegroups.com. Visit this group at http://bit.ly/1dkFnYd. For more options, visit http://bit.ly/P65DvS.