Rails - Jul 2006 - Issues with has_many, belongs_to and dependency settings

I have 2 models SmsAddress & OutboundSmsAtom

SmsAddress {

has_many :other_objects, :dependency => :nullify

}

OutboundSmsAtom {
    #note this object also "belongs_to" other objects if that matters
    belongs_to :this_object
    
}

Whenever I try to destroy an object of type ThisObject, which at the time
has 0 "children" OtherObjects I get the following type of error
message
>> address.destroy
NameError: uninitialized constant OuboundSmsAtom
        from 
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependenc
ies.rb:100:in `const_missing''
        from 
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependenc
ies.rb:131:in `const_missing''
        from 
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependenc
ies.rb:133:in `const_missing''
        from (eval):1:in `configure_dependency_for_has_many''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/callbacks.
rb:337:in `callback''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/callbacks.
rb:330:in `callback''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/callbacks.
rb:320:in `destroy_without_transactions''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactio
ns.rb:122:in `destroy''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/connection
_adapters/abstract/database_statements.rb:51:in `transaction''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactio
ns.rb:91:in `transaction''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactio
ns.rb:118:in `transaction''
        from 
/usr/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactio
ns.rb:122:in `destroy''
        from (irb):18
>> exit
If I turn of the :dependent property it then works fine.  I''m sort of
stumped.  Thanks in advance if anyone has a fix, or even better a fix for
what must be some sort of conceptual mistake I''m making.

Cheers - Shane