ActiveRecord model design help

I need some help on the following model design :

User model (user.rb) class User < ActiveRecord::Base    has_many :analyses, :dependent => :destroy

Analysis model (analysis.rb) class Analysis < ActiveRecord::Base   belongs_to :instructor, :class_name => "User", :foreign_key => :instructor_id   belongs_to :member, :class_name => "User", :foreign_key => :member_id

creating an analysis works Analysis.create(:instructor_id => 1, :member_id => 2, :status => "pending") I can get : Analysis.first.instructor Analysis.first.member

BUT User.find(1).analyses raise an error : ActiveRecord::StatementInvalid: Mysql::Error: Unknown column 'analyses.user_id' is there any way to handle this design ?

thanks a lot for your help

(btw I use the inflection plural analysis -> analyses)