I think I've found the problem and fixed it. Try posting in there again astronut. The most recent post I found in there was May of 2012. Somewhere about that time, it looks like posting permission was removed from that forum. Perhaps by request from AM (I'm not sure).
I'll check with them to see if they made that request. If they did, then there will be an announcement added to the top of their forum.
In the meantime, you should now be able to post in that forum. Post here, if that is not the case.