I am commenting on an answer to a question I wrote. I clicked the "Add Comment" button under the answer and the edit window opened and I typed my comment, then when I click the SECOND "Add comment" button to the right of the edit box, it does nothing. Why. I am using Firefox and I have commented on questions before, so I don't think it is a simple java-script issue as others have pointed out.
If you go over the 600 character limit in a comment (or under 15), the "Add Comment" button simply does nothing. Sigh.