foreign key not working

Hello,

I'm using InstantRails 1.6 on Windows XP with Mysql 5.0.27, Rails
1.2.2, and Ruby 1.8.5.

The following foreign key is not working.

class FkLibriid < ActiveRecord::Migration
  def self.up
    execute "alter table my_items
             add constraint fk_myid
             foreign key (myid) references products(myid)"
  end

  def self.down
  end
end

I declared myid in both tables the same:
t.column :myid, :integer, :null => false

And myid is not primary key in any table. I don't like it to be one.

Additionally, I've set the following in the model for the referenced
table:
validates_uniqueness_of :myid

C:\Myshop\shop>rake db:migrate --trace
(in C:/Myshop/shop)
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute db:migrate
== FkLibriid: migrating