Help needed in Routes

Hi All

I am now using Rails 2.3.4 i would want to have a route like http://localhost:3000/mysite/questions/show.xml/question-title

In Rails 2.1.2, i had used the format map.namespace :mysite do |mysite|

    mysite.show_question '/questions/show.:format/:title', :controller => 'mysite_questions', :action => 'show'


But now the same route shows up an error in Rails 2.3.4.I am not able to start the application even. Kindly tell me what should be followed so that the application runs.

Thanks In Advance,