recapcha version 2 images not appreasring

We have done java implementation of recapcha version 2. We are getting strange error where on click of checkbox Im not robot image list doesn't appear. And this happens 30% of time approx. We tried same across IE, Mozilla and chrome. Need help. Thanks, Abhi -- 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.