I have a PDF version 1.5 here which I started commenting on with Foxit Reader 4. If I open the commented PDF in Adobe Reader 9 now, I get the following message:
This document enabled extended features in Adobe Reader. The document has been changed since it was created and use of extended features is no longer available. Please contact the author for the original version of this document.
The document properties in Adobe Reader say that the document is not allowed to be commented.
How can I prevent this and keep the document commentable in both Foxit and Adobe Reader?