Your code is wrong, I runned the following with no problem: require 'og' class A property :koko, String end class AA < A property :haha, String end Og.start a = A.create aa = AA.create oid = 1 b = A[oid] # no problem am I missing something? -.g -- http://www.gmosx.com http://www.navel.gr http://www.nitrohq.com