Cannot do mass_assignment when inherited class?

I got the following error when trying to create the elibrary instance

(rdb:21) @elibrary =[:elibrary])
RuntimeError Exception: Declare either attr_protected or
attr_accessible for Elibrary, but not both.

params : “elibrary”=>{“title”=>“bingo three”,
“short_description”=>“something new”, “description”=>“


Elibrary is declared as inherited from MediaItem, and attr are
declared accessible in MediaItem…

class MediaItem < ActiveRecord::Base
belongs_to :media_container


attr_accessible :title, :short_description, :description

class Elibrary < MediaItem

when @elibrary =, then assigning attributes to @elibrary,
save is OK…

1- even duplicatiing the attr_accessible in both classes doesn’t help
2- acts_as_nested_set brought additional fields … ant issue with it ?

The error is somewhere in your class declaration, but the message
you’re getting doesn’t appear until you run attributes=.
I’d look at the other plugins you’re using, as somebody’s calling
attr_protected on MediaItem.

–Mat Jones