recent issue, had sold many pistons today but in last 10 mins both my piston shop stop working -they both have stock -signs are correct -tried remaking and even buying myself with an alt so far only my pistons shops seem to be having this issue
This issue has already been addressed, Aikar is working on it but it is not a top priority of his. You can use this setup: Deathtomb8953 1 B 5:1 S [Slot 54] or [Slot 27]
I believe Aikar has re-mapped the item ID for this (and quartz slabs which aren't supported in chest shops yet) and is almost ready to deploy it's update to servers, from what he has said on SMP2. Right now when you do /iteminfo it gives you the correct ID that it must have been changed to, try using that for now or you could wait. More info: http://empireminecraft.com/threads/bug-report-shop-signs.23461/