I have been getting a strange error message and I can't figure out
what's causing it, and haven't found the answer online anywhere. The
error message says "Can't convert String into Integer" with this stack
trace:

c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/association\
s/association_proxy.rb:123:in
`[]'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/association\
s/association_proxy.rb:123:in
`send'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/association\
s/association_proxy.rb:123:in
`method_missing'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/association\
s/has_many_association.rb:98:in
`method_missing'
(eval):1:in `id'
#{RAILS_ROOT}/app/controllers/admin_controller.rb:525:in `create_option'

This is the function from controllers/admin_controller.rb

521: def create_option
522: @option = Option.new do |o|
523: o.name = "New Option"
524: end
525: @option.save
526: respond_to do |format|
527: format.js do
528: render :update do |page|
529: page.insert_html :bottom, "options", {:partial =>
'option', :object => @option}
530: end
531: end
532: end
533: end

and models/option.rb

class Option < ActiveRecord::Base
has_many :attributes, :dependent => :destroy
has_many :values, :through => :attributes
end

I have tried replacing "New Option" with a number and changing the id
field to varchar(255) neither worked; this looks like something in the
save function is going wrong and I'm getting a useless error message.
If anyone has encountered and solved this problem, I would appreciate
a tip.

Thank You.