I don't see that option under the advanced menu. I do however see an option under the comments menu that says "enable for commenting in Adobe Reader." I did try this option but it only allows the user to place comments on the form and they cannot fill out the form.
Any other suggestions you might have? Thanks for your help!!!
I've been dealing with the same issue and I found that when I went into the Advanced menu and selected to enable the usage rights, it said that the file already had them. I did a "save a copy" which removed the rights and then re-issued the rights with the Advanced menu. The file seems to be functioning fine in Reader, I was able to enter data into the fields, close the file and it was still there when I reopened it.