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The issue that you are experiencing has to do with the link that is being used in the iFrame code. The edit link is being used and this prevents the documents form showing up.
Please edit the link and use the follow: https://drive.google.com/file/d/0BzpDSnGLBtLBY0tfUFpmWGs5TVE/preview
I cloned your form and made the change, your can view the cloned form here: http://jotform.com/form/50045118539957
You can clone this form to your account.
I hope this helps! Please inform us if you need further assistance.