captcha popup keep dissapearing without user input

Captcha popup keep disappearing without allowing users to choose the correct image. I have been trying to fix this for two days but it is still not working. I have used both the direct way as well as explicit way for displaying my captcha. And by the way my captcha is on a pop up registration form. Please help -- 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.