Weird error after upgrading to rails 3.0.4

Hey folks,

have you seen this ever?

[user@i ~/rails_project]$ rake rails:update --trace (in /usr/home/rails_project) rake aborted! uninitialized constant ActiveModel::Validations::HelperMethods /usr/local/lib/ruby/gems/1.8/gems/activemodel-3.0.4/lib/active_model/ validations.rb:50 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.4/lib/ active_support/concern.rb:52:in `class_eval' /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.4/lib/ active_support/concern.rb:52:in `append_features' /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.4/lib/ active_support/concern.rb:48:in `include' /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.4/lib/ active_support/concern.rb:48:in `send' /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.4/lib/ active_support/concern.rb:48:in `append_features' /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.4/lib/ active_support/concern.rb:48:in `each' /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.4/lib/ active_support/concern.rb:48:in `append_features' ...

Regards, Istvan