error on belongs_to method.

I followed the Ruby on Rails up and running book published by Orielly.
there are three DB tables, photo, slideshow, and slide

the Slide class in slide.rb is like this:
class Slide < ActiveRecord::Base
  belongs_to :photo :foreign_key =>photo_id
  belongs_to :slideshow :foreign_key=>slideshow_id
end

I inserted the sample data into database. When I trying to run the
command on page39:
slide= Slide.find 1
it give me the following error:
../slide.rb:2: syntax error, unexpected ';', expecting kEND.
and the same with ../slide.rb:3

can anybody help me? if you can tell me how to debug rails, that will
be more better? thanks in advance.

sorry for asking a so stupid question.
I found that I missed the commas.