Error while using PDF Kit

I am trying to use PDFKit using rails 3, I followed the railscast tut开发者_开发知识库orial and found that I get the following error:

: undefined method `wrap_parameters' for ActionController::Base:Class (NoMethodError)

http://railscasts.com/episodes/220-pdfkit

Maybe you're accidentally loading Rails 3.0.x on a Rails 3.1 application?

It won't work if you generate a Rails 3.1 application, which adds config/initializers/wrap_parameters.rb, and then try to boot it with Rails 3.0.x.

If you want Rails 3.1: Are you running with bundler, e.g. bundle exec unicorn_rails or bundle exec rake?

If you want Rails 3.0.x: Regenerate the application by running rails new appname to see what needs to change.