That addon has not been updated to the most current version of WoW. You can enable in 2 ways.
1) Check the load out of date addons box on the addons selection screen found on the bottom left corner of the character selection screen.
2) Open the addons folder and find a file inside with the exstension ".toc" open the file with notepad and find a number in there that says 20400 and change it to 30000.
It will now load but there is a chance that there will be errors related to changes in the WoW API. This addon seems as though it is slipping into the void as far as updates are concerned. Good luck and i hope it helps.

P.S. wowinterface.com is another site that has tons of addons and you can often find addons there that are otherwise impossible to find such as "ohnoes" the blink your screen red when follow breaks addon.