RoR and Facebook Apps

Hey everybody,

I am trying to code a small application in FB in order to learn how to
do it with RoR, but I run into the following problem once I already can
connect to my application:

Swapping facebooker config: 'd1591b2c19797dcd182e8232c75ee662'
  e[4;36;1mSQL (2.0ms)e[0m e[0;1mSET NAMES 'utf8'e[0m
  e[4;35;1mSQL (3.0ms)e[0m e[0mSET SQL_AUTO_IS_NULL=0e[0m

Processing MainController#index (for at 2010-08-06
15:41:54) [GET]
  Parameters: {"fb_sig_in_canvas"=>"1", "fb_sig_request_method"=>"GET",
"fb_sig_locale"=>"en_US", "fb_sig_in_new_facebook"=>"1",
"fb_sig_time"=>"1281102112.3388", "fb_sig_added"=>"0",
"fb_sig_country"=>"es", "fb_sig_api_key"=>"...", "fb_sig_app_id"=>"...",

ActionController::UnknownAction (No action responded to index. Actions:
create_facebook_session, create_facebook_session_with_secret,
facebook_params, facebook_session, facebook_session_parameters,
one_or_true, redirect_to, render_publisher_error,
render_publisher_interface, render_publisher_response,
set_facebook_session, top_redirect_to, wants_interface?, and
  <internal:prelude>:8:in `synchronize'
  C:/Ruby191/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
  C:/Ruby191/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
  C:/Ruby191/lib/ruby/1.9.1/webrick/server.rb:183:in `block in


I am not really sure of what it could be, but if I point my browser to
http://localhost:3000/ I can see a rendered text I wrote in order to
know whether the app was running fine or not, but once I go to my app's
facebook page, I get the ActionController::UnknownAction error..

Thanks a lot in advance!