0.0.12 and 0.0.11 should be fine, but he says he isn't able to activate the plugin. Are you seeing any messages in the server console when you click activate?
Unexpected end of JSON input on Avatar Upload
This might be one of those Schrodinbugs, but I got an
Unexpected end of JSON inputwhile trying to upload an avatar.
This was after trying a few times, and getting rebuffed for having really big avatars. And finally, I found one which wasn't gigantic and it went up.
After that, I decided that I didn't like that avatar and swapped it for another one, and I got that strange error, but the avatar went through, from the looks of it
To clarify, this happened on these very forums.