I took a look at Drek's fence and it looks like it may have some glitches. I have one here that is mostly complete that I worked on about a month ago. It differs enough from Drek's so it might not be the best one because it would have to be tacked on to his other panel fences to have everything match up. A lot of extra work. But I figured I would show it anyway. We'll see how Drek's ends up first.
OOPS. I see we posted at about the same time.
ADDED. In my modeling program it looked like the middle posts on your's were twisted or walls collapsed and not aligned right. I don't see it in the screen shot though.