Rubyamf with attachment_fu problem.

Question

This my class test.

has_attachment :storage => :file_system,
  :max_size => 1.megabytes

Rubyamf_config.rb

ClassMappings.register(
  :actionscript  => 'TestVO',
  :ruby          => 'Test',
  :type          => 'active_record',
  :methods       => ["created_at","has_attachment"],
  :attributes    => ["id","document_uri", "lock_version"])

I have set has_attchment as method in rubyamf config but i am getting error like undefined method has_attachment.

And i have also tried to set has_attachment as attributes in rubyamf_config but getting same error.

I have used plugin attachment_fu and this method is defined in attachment_fu.rb file.

so how i have to pass this has_attachment in rubyamf_config ??