Ruby on Rails

I'm having an issue with one migration.  all other migrations work ok.

Here's the output:
== 20140905145859 CreateMemberships: migrating
================================
-- create_table(:memberships)
   -> 0.3010s
== 20140905145859 CreateMemberships: migrated (0.3011s)
=======================


But here's what it looks like in rails c:
Loading development environment (Rails 4.0.5)
2.0.0-p481 :001 > Membership
 => Membership()

Here's the content of the migration:
class CreateMemberships < ActiveRecord::Migration
  def change
    create_table :memberships do |t|
      t.string :user_id

      t.timestamps
    end
  end
end


Any ideas why this one migration has problems?