[Nitro] is Orderable weird exception

[Aureliano Calvo]

I'm trying to use the Orderable mix in and I'm getting a weird error:

/usr/lib/ruby/gems/1.8/gems/facets-1.8.54/lib/facets/more/paramix.rb:96:in
`is': undefined method `basename' for :Orderable:Symbol
(NoMethodError)
	from /usr/lib/ruby/gems/1.8/gems/facets-1.8.54/lib/facets/more/paramix.rb:94:in
`each'
	from /usr/lib/ruby/gems/1.8/gems/facets-1.8.54/lib/facets/more/paramix.rb:94:in
`is'
	from ./spec/model/helper/../../../app/model/question.rb:4

class Question
  attr_accessor :text, String
  belongs_to :survey
  is Orderable, :scope => :survey # this is the offending line
end

Any ideas?

Aureliano.