I've purchased Wiki plugin and still try to figure out how I can work properly.
I tested Wiki's History function on twenty eleven theme(defualt theme).
As you can see on the link below,
1) Compare Revisions: doesn't work. It always goes previous archive page.
2) Restore: doesn't work. It shows me the message like below even if the page exists.
"Wiki page you are looking for does not exist. Feel free to create it yourself."
Please confirm those functions.