Is the post reply missing from both the top and the bottom ? You only mentioned the bottom.

Here is a suggestion.

Use the reply with quote button which is the third icon on every posted message. Just remove the quoted material before posting and you get the same result as reply. That's how I posted this message just to test my idea. I am assuming these icons are showing up for you....

Looking at the source for the page it seems they are using a table to layout the buttons perhaps your browser is having trouble with tables ?