As far as I am aware the last few Dormice were removed from that enclosure a few months ago and mixed with the Pouched Rats. I was told that they have since died out. Their old enclosure in Twilight remained furnished and with signage, but was indeed empty.
Just to add to the confusion I saw a Dormouse in with the Pouched Rats on the 1/1/2012 when I visited,it was only a view of one peeking out of a nest box but still a view.