I've already followed the steps posted here: http://forums.adobe.com/thread/430906 and enabled highlighting under preferences but i'm still unable to highlight or comment.
I am sure the document allows commenting as I was able to highlight and comment using campus computers but not my personal laptop.
Please help! Thanks!
The PDF has to be specially enabled by someone using Acrobat in order for that to work.
The campus computers may have a version of Acrobat and that's why you can do it there.