Active_record error

hi, I am trying to connect to mysql server via active record :

require ‘rubygems’
require ‘active_record’

:adapter => “mysql2”,
:host => “localhost”,
:database => “xxxxxxx”,
:username => “root”,
:password => “xxxxxxx”,
:encoding => “utf-8”

but I am getting error message:
/usr/lib/ruby/vendor_ruby/active_support/dependencies.rb:131:in rescue in const_missing': uninitialized constant ActiveRecord::ConnectionAdapters::AbstractAdapter::SchemaCreation (NameError) from /usr/lib/ruby/vendor_ruby/active_support/dependencies.rb:120:inconst_missing’…

I can connect to the server using mysql2 client directly

Am I doing something wrong? How can I correct this problem