Acrobat Pro Illustrator CS PDF Problem

[CoreyShelton@adobeforums.com]

I'm trying to edit an existing PDF with fields in Illustrator CS
while maintaining the PDF funtionality.

I USED to be able to open the PDF in Acrobat 6.0, then "save as"
something, then open in Illustrator 9 and change text, resave it
and things would still work for other users using Reader.

Now, I have Acrobat Pro, and Ill CS, and I can't get this to work.
I'm just making Fax covers, but need to make a lot of personalized
ones.

Any suggestions would be appreciated.

Corey Shelton