Comment: Error: This file cannot be used on its own

Hi, I need some help since my comments won’t work. I’ve tried looking through other topics but haven’t found a solution to this yet.
url: http://tvb.windy-goddess.net/

When anyone (including myself) try to comment, it comes up with this: “Error: This file cannot be used on its own.” and that’s it..

Thanks in advanced 🙂