Sorry guys, I think this may be an API bug. Try refreshing your chart. The sell price at gox is at 5.67ish as far as I can tell, and I tested that by setting a small order at 5.56, which went through.
The problem is that the ask and bid walls are not moving with the live events.
when you hit refresh you get the wrong or old "ask bid" positions.
We are at 6 now