Adobe Reader Commenting Not Allowed
At last! Wanted to allow my prof. to be able to comment the pdf files that my LaTeX produces. But, even though I was NOT setting any such restrictions in LaTeX, the Adobe Reader always showed that Commenting was not allowed. After a Google search, I got this post in the Adobe Forums: http://www.adobeforums.com/webx/.3c05f5b1
In short: You cannot comment unless explicitly permitted. For this, you need to get to Adobe Acrobat (not the reader), and set the permission from: Commenting > Enable for Commenting in Adobe Reader.
Then you will be allowed to comment or markup :)
Update: If you don’t mind a few additions of Foxit, you might want to try Foxit reader(www.foxitsoftware.com) for commenting your PDF documents without any of the above hassle.