SystemStackError: stack level too deep in activemerchant

I am using activemerchant 1.3.2 with rails 1.2.3

when i submit CC for validation:

following code in controller

ActiveMerchant::Billing::Base.mode = :test creditcard1 = ActiveMerchant::Billing::CreditCard.new( :first_name => 'Bob', :last_name => 'Bobsen', :number => '4142424242424242', :month => '09', :year => '2012', :verification_value => '123' )

if creditcard1.valid? ...

Then i get error : SystemStackError: stack level too deep

c:/ruby/lib/ruby/1.8/date/format.rb:661:in `s3e' c:/ruby/lib/ruby/1.8/date/format.rb:861:in `_parse_sla_us' c:/ruby/lib/ruby/1.8/date/format.rb:975:in `_parse' c:/ruby/lib/ruby/1.8/time.rb:240:in `parse' #{RAILS_ROOT}/vendor/plugins/active_merchant/lib/active_merchant/ billing/expiry_date.rb:16:in `expiration' #{RAILS_ROOT}/vendor/plugins/active_merchant/lib/active_merchant/ billing/expiry_date.rb:12:in `expired?' #{RAILS_ROOT}/vendor/plugins/active_merchant/lib/active_merchant/ billing/credit_card.rb:62:in `expired?' #{RAILS_ROOT}/vendor/plugins/active_merchant/lib/active_merchant/ billing/credit_card.rb:136:in `validate_essential_attributes' #{RAILS_ROOT}/vendor/plugins/active_merchant/lib/active_merchant/ billing/credit_card.rb:95:in `validate' #{RAILS_ROOT}/vendor/plugins/active_merchant/lib/active_merchant/lib/ validateable.rb:7:in `valid?'

if i skip check expiry? then again i see same error at checksum

Please Help