Error while uploading images using attachment_fu on windows

I am a newbie to Rails and i am trying the attachment_fu plugin. I am referring to the post from the url http://clarkware.com/cgi/blosxom/2007/02/24

When i try to upload an image i am getting the below error. I am using RMagick. Instead of max_size, i am using size for the attachment options in the model.

undefined method `include?' for 512000:Fixnum

vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu.rb:381:in `attachment_attributes_valid?' vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu.rb:379:in `each' vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu.rb:379:in `attachment_attributes_valid?' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ validations.rb:1000:in `send' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ validations.rb:1000:in `run_validations' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ validations.rb:998:in `each' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ validations.rb:998:in `run_validations' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ validations.rb:962:in `valid_without_callbacks?' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ callbacks.rb:273:in `valid?' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ validations.rb:933:in `save_without_transactions' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ transactions.rb:108:in `save' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ connection_adapters/abstract/database_statements.rb:66:in `transaction' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ transactions.rb:80:in `transaction' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ transactions.rb:100:in `transaction' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ transactions.rb:108:in `save' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ transactions.rb:120:in `rollback_active_record_state!' c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ transactions.rb:108:in `save'

Can someone help in resolving this issue.