corrected last migration

db/migrate/20111021101550_change_social_fields_in_users.rb

 class ChangeSocialFieldsInUsers < ActiveRecord::Migration
   def up
-  	change_column(:users, :skype, :string, {:null => false, :default => ''})
-  	change_column(:users, :linkedin, :string, {:null => false, :default => ''})
-  	change_column(:users, :twitter, :string, {:null => false, :default => ''})
+    remove_column :users, :skype
+    remove_column :users, :linkedin
+    remove_column :users, :twitter
+
+    add_column :users, :skype, :string, {:null => false, :default => ''}
+    add_column :users, :linkedin, :string, {:null => false, :default => ''}
+    add_column :users, :twitter, :string, {:null => false, :default => ''}
   end
 
   def down