Cannot answer question: "Missing required fields."

http://www.stseverus.ca/index.php/q-a/view/2-test-question

When I try to answer this question, it gives an error message "Missing required fields."

The only field I see is the answer text area, and there is text there.

Also, when I click on a question when not logged in, it says "please log in to continue" despite the fact that the category is set to public view / ask / answer.

Any help would be appreciated. Thank you.