can't dup NilClass when trying to add an object to a list

[MagmaRules]

Here is my code: http://pastie.org/456077
The first time i run it, it goes ok. The second time it blows up when i add the event to the list.

It seems the second time it passes the "if record['polymorphic_parent_class']" in base.rb. The first time it doesnt enter the if.

can't dup NilClass
/Users/magmarules/Sites/Probono/vendor/plugins/has_many_polymorphs/lib/has_many_polymorphs/base.rb:14:in dup' /Users/magmarules/Sites/Probono/vendor/plugins/has_many_polymorphs/lib/has_many_polymorphs/base.rb:14:ininstantiate'
/Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:635:in find_by_sql' /Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:635:incollect!'
/Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:635:in find_by_sql' /Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:1490:infind_every'
/Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:589:in find' /Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/associations/has_many_through_association.rb:73:infind_target'
/Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/associations/association_collection.rb:344:in load_target' /Users/magmarules/Sites/Probono/vendor/plugins/has_many_polymorphs/lib/has_many_polymorphs/association.rb:19:in<<'
/Users/magmarules/Sites/Probono/lib/tasks/import.rake:222
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:617:in call' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:617:inexecute'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:612:in each' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:612:inexecute'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:578:in invoke_with_call_chain' /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/monitor.rb:242:insynchronize'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:571:in invoke_with_call_chain' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:564:ininvoke'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:2027:in invoke_task' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:2005:intop_level'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:2005:in each' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:2005:intop_level'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:2044:in standard_exception_handling' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:1999:intop_level'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:1977:in run' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:2044:instandard_exception_handling'
/Library/Ruby/Gems/1.8/gems/rake-0.8.4/lib/rake.rb:1974:in run' /Library/Ruby/Gems/1.8/gems/rake-0.8.4/bin/rake:31 /usr/bin/rake:19:inload'
/usr/bin/rake:19

[MagmaRules]

Sorry my bad, i have the object named event and the relation named events and that was the problem.