I cannot for the life of me figure out why the Tools and Comment tabs show, but the Sign tab does not. I can no longer digitally sign PDFs. I re-installed, and was able to sign once again, but then the sign tab once again disappeared.
I don't know if I can sign re-saved fillable documents prior to signing, but when I open the reader itself with no file, it still won't show the tab. What's going on?
I am having the same problem. I created a form in Lifecycle Designer. All my Acrobat 9 users can sign and save. All my Acrobat Pro XI users cannot sign, and when they save, all their input data is lost. The security settings are enabled in my 9 users, but dimmed for my XI users!
Can you sign in Acrobat XI by clicking on the signature field?
Is there a yellow bar at the top warning about unsafe files and that you can enable features? If so, this could be the cause. Protected view disables most features and you need to enable them before signing.