Foxy Fixtures and Polymorphism not running properly

I would like to hear ideas about a problem I'm having with testing a controller from a model that uses polimorphism. It seems that the fixture do not recognize the relationship. Did you see errors in these files? The error I get is:

/***** ERROR *****/   1) Error: test_should_show_ingreso(IngresosControllerTest): ActionView::TemplateError: You have a nil object when you didn't expect it! The error occurred while evaluating nil.nombre     On line #18 of app/views/ingresos/show.html.erb

        15:         16: <p>         17: <b>Origen</b>         18: <%=h @ingreso.origen_type %>: <%= @ingreso.origen.nombre %>         19: </p>         20:         21:

        app/views/ingresos/show.html.erb:18         app/controllers/ingresos_controller.rb:86:in `show'         /test/functional/ingresos_controller_test.rb:32:in `test_should_show_ingreso'         c:/ruby/lib/ruby/1.8/test/unit/testsuite.rb:34:in `run'         c:/ruby/lib/ruby/1.8/test/unit/testsuite.rb:33:in `each'         c:/ruby/lib/ruby/1.8/test/unit/testsuite.rb:33:in `run'         c:/ruby/lib/ruby/1.8/test/unit/testsuite.rb:34:in `run'         c:/ruby/lib/ruby/1.8/test/unit/testsuite.rb:33:in `each'         c:/ruby/lib/ruby/1.8/test/unit/testsuite.rb:33:in `run'         c:/ruby/lib/ruby/1.8/test/unit/ui/testrunnermediator.rb:46:in `run_suite'         c:/ruby/lib/ruby/1.8/test/unit/ui/console/testrunner.rb:67:in `start_mediator'         c:/ruby/lib/ruby/1.8/test/unit/ui/console/testrunner.rb:41:in `start'         c:/ruby/lib/ruby/1.8/test/unit/ui/testrunnerutilities.rb:29:in `run'         c:/ruby/lib/ruby/1.8/test/unit/autorunner.rb:216:in `run'         c:/ruby/lib/ruby/1.8/test/unit/autorunner.rb:12:in `run'         c:/ruby/lib/ruby/1.8/test/unit.rb:278         rake (0.8.7) lib/rake/rake_test_loader.rb:5

/***** clientes.yml *****/ jack:   NIF: B98654321   nombre: Jack

/***** ingresos.yml *****/ primero:   origen: jack (Cliente)

/***** cliente.rb *****/ class Cliente < ActiveRecord::Base   has_many :ingresos, :as => :origen end

/***** ingreso.rb *****/ class Ingreso < ActiveRecord::Base   belongs_to :origen, :polymorphic => true end

/***** test_ingresos_controller.rb *****/   test "should show ingreso" do     get :show, { :id => ingresos(:primero).to_param }, { :usuario_id => usuarios(:fulanito).id }

    assert_response :success   end

/***** views/ingresos/show.html.erb <p>   <b>Origen</b>   <%=h @ingreso.origen_type %>: <%= @ingreso.origen.nombre %> </p>

Any help will be appreciated. Thanks in advance.