Ah yes, the problem may really be within your browser.
Even though I don't think you have expanded Web Editor Tools on your browser, you should try to check if you have NoScript enabled or JavaScript disabled.
Ah, also, like Alikaey said, you can always use the built-in for all forumotion forums /chatbox URL, which would just simply be http://duelacademy.net/chatbox
Now, any other questions about this subject?