I want to implement 236-omniauth-part-2 in my Project But i get error

[regmiprem]

NoMethodError in AuthenticationsController#create

undefined method `find_by_provider_and_uid' for Authentication:Class

I define it in stackoverflow. http://stackoverflow.com/questions/13561140/i-am-using-rails-cast-omniauth-and-i-get-this-error