NoMethodError caught when I'm trying destroy the rated object

[ghost]

I've decided using gem letsrate in my app, but I have some problem, probably caused by gem.

First some code:

I've got a model Article:

class Article < ActiveRecord::Base
  letsrate_rateable "quality"
  ...
end

and model User (generated by Devise):

class User < ActiveRecord::Base
  letsrate_rater
  ...
end

I've used generator according to readme instructions:

rails g letsrate user

Everything works great until I try destroy my article object, then I've got this error:

>> Article.last.destroy
Article Load (0.4ms)  SELECT `articles`.* FROM `articles` ORDER BY `articles`.`id` DESC LIMIT 1
   (0.1ms)  BEGIN
  Rate Load (0.4ms)  SELECT `rates`.* FROM `rates` WHERE `rates`.`rateable_id` = 1 AND `rates`.`rateable_type` = 'Article' AND `rates`.`dimension` IS NULL
  SQL (0.3ms)  DELETE FROM `rates` WHERE `rates`.`id` = 2
  RatingCache Load (1.2ms)  SELECT `rating_caches`.* FROM `rating_caches` WHERE `rating_caches`.`cacheable_id` = 1 AND `rating_caches`.`cacheable_type` = 'Article' AND `rating_caches`.`dimension` IS NULL LIMIT 1
  SQL (1.0ms)  DELETE FROM `rating_caches` WHERE `rating_caches`.`id` = 2
  Rate Load (0.3ms)  SELECT `rates`.* FROM `rates` WHERE `rates`.`rateable_id` = 1 AND `rates`.`rateable_type` = 'Article' AND `rates`.`dimension` = 'quality'
  Rate Load (0.3ms)  SELECT `rates`.* FROM `rates` WHERE `rates`.`rateable_id` = 1 AND `rates`.`rateable_type` = 'Article' AND `rates`.`dimension` = 'quality'
   (0.5ms)  ROLLBACK
NoMethodError: undefined method `association_class' for nil:NilClass
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/associations.rb:159:in `association'
from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/associations/builder/has_one.rb:49:in `has_one_dependent_destroy_for_quality_average'
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-3.1.6/lib/active_support/callbacks.rb:422:in `_run_destroy_callbacks'
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-3.1.6/lib/active_support/callbacks.rb:81:in `run_callbacks'
from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/callbacks.rb:254:in `destroy'
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/transactions.rb:236:in `block in destroy'
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/transactions.rb:295:in `block in with_transaction_returning_status'
from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/connection_adapters/abstract/database_statements.rb:194:in `transaction'
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/transactions.rb:208:in `transaction'
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/transactions.rb:293:in `with_transaction_returning_status'
from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.1.6/lib/active_record/transactions.rb:236:in `destroy'
  from (irb):1
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.1.6/lib/rails/commands/console.rb:45:in `start'
  from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.1.6/lib/rails/commands/console.rb:8:in `start'
from /Users/xyz/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.1.6/lib/rails/commands.rb:40:in `<top (required)>'
  from /Users/xyz/projekty/dentist/script/rails:6:in `require'
  from /Users/xyz/projekty/dentist/script/rails:6:in `<top (required)>'
from -e:1:in `load'
  from -e:1:in `<main>'

The error occures no matter if I use quality dimension or not. I will be very grateful for your reply where the problem is.

PS. Im'using the newest version of gem (letsrate (1.0.7))