Signature wont show for members

Hi I'm an admin on a small forum site and we've just updated the theme, cleaned out the old posts etc,

but on re-registering, members cannot get a sig to display even though it shows in their preview,
we have checked the admin panel and its turned on for all, I've checked to ensure they know about turning it on for themselves, but nothing will get it to show,

is there currently a bug with PhpBB2 or is the problem in our code,

address is http://www.oracletravian.com/

Thanks in advance for any help