RoR: up and running problem in book example

Hey everyone, im a new RoR user and i am running into a glitch at page
41 of the RoR: up and running book photo share example. I am using OSX
10.4, locomotive, and PHPmyadmin through MAMP.

in the book it says to see the model in action.

slide = Slide.find 1


slideshow = slide.slideshow


slideshow.slides.each {|slide| puts}

when i enter in the last line slideshow.slides.each {|slide| puts} I get the following:

NoMethodError: undefined method `slides' for #<Slideshow:0x2427cac>
        from (irb):11

but i have followed the book really closely. any help as to what i am
missing or may have forgot? Everything else had worked up till now.

my bad, i forgot to rake migrate after i changed the code.