Restful web service error on saving record

Error is: NoMethodError: You have a nil object when you didn't expect it! You might have expected an instance of ActiveRecord::Base. The error occurred while evaluating nil.         from /www/gems/gems/activeresource-2.0.2/lib/active_resource/ base.rb:817:in `id_from_response'         from /www/gems/gems/activeresource-2.0.2/lib/active_resource/ base.rb:804:in `create'         from /www/gems/gems/activesupport-2.0.2/lib/active_support/ core_ext/object/misc.rb:28:in `returning'         from /www/gems/gems/activeresource-2.0.2/lib/active_resource/ base.rb:803:in `create'         from /www/gems/gems/activeresource-2.0.2/lib/active_resource/ base.rb:636:in `save_without_validation'         from /www/gems/gems/activeresource-2.0.2/lib/active_resource/ validations.rb:262:in `save'         from /data/www/rails/authentication/app/models/account.rb: 89:in `create_notification'         from /www/gems/gems/activerecord-2.0.2/lib/active_record/ associations/association_proxy.rb:125:in `send'         from /www/gems/gems/activerecord-2.0.2/lib/active_record/ associations/association_proxy.rb:125:in `method_missing'

Client: notification_email.rb model class NotificationEmail < ActiveResource::Base   self.site = "[http://mysite]" end

I use the model class to create a new object. Error happens on save. def create_notification        n = NotificationEmail.new        n.save end

Web service set up is very simple. It basically saves the record to the database. I tested it with curl and it works. Anyone has any ideas what this error message means?

Thank you!