Unable to edit text and images using Adobe acrobat Xi pro which is part of creative cloud

Hi Team,

I have been unable to edit most of the PDF's using adobe acorbat xi pro and I end up getting attached error message when I try Edit option under Tools. Can you please advise ? OS - I have tried both win 7 32 and 64 bit. It works for few Pdf's but not for all.

Regards,

Yprasad