Recaptcha buttons not working on dinamically added form

I have a user registration system that uses reCaptcha. The registration form is dynamically added in a modal window and uses AJAX for validation. Everything is working except for the reCaptcha buttons - new challenge, audio, help. I assume this can be because the modal window was added dynamically. Do you guys have any idea how to debug this? -- 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.