OK on the page that wasn't showing the editor, you had the editor named "description"... but there was a meta tag named "description" causing a conflict. I renamed it to postdescription.
On the other page it was already called postdescription. I updated the php to use postdescription, but didn't notice that the form action was still pointing to the other page that had it wrong. I've updated the update code to postdescription on the original page as well now, so it should work in both.