amistad-0.9.2/lib/amistad/friendship_model.rb:9:in `included'

[railsfactory-deepikakg]

I'm using rails 3.2.5 with activerecord 3.2.5, and ruby 1.9.3
i tried to implement amistad gem for maintaining friendship within my application.
I have added "include Amistad::FriendshipModel" in my user model. but i don't see any methods included in mys user model. I have to know if there is any problem for amistad with activerecord 3.2.5? whether this will work or not with this version of activerecord.
It throws error like:

RuntimeError: Amistad only supports ActiveRecord and Mongoid
from C:/Ruby193/lib/ruby/gems/1.9.1/gems/amistad-0.9.2/lib/amistad/friendship_model.rb:9:in `included'

When i try with my console. any methods from amistad like invite, approve are throwing errors as undefined method "invite"

Please help me