Cannot post replies

There's two ways you can post replies. A "Quick reply" is right here when viewing a thread, which I'm using now.
Another way is to press the "New reply" button under the last comment in a thread.

Which one are you trying to use? And if you press "post reply" here without writing anything it will not post anything, just reload this quick reply section =)

Edit: Ahh, yes. You are correct! The New Reply editing page is not working. Shall look into it. Meanwhile, try using the quick reply which is present directly in a thread.