401 Unauthorized error in Rails two-legged OAuth provider - ruby-on-rails-3

Question

I'm trying to implement a two-legged OAuth provider on Rails.
I followed these instruction for installing the consumer and provider:
https://github.com/pelle/oauth-plugin
with these instructions to make the consumer work
Rails3 - oauth-plugin problem
These instruction to implement the user login
https://github.com/plataformatec/devise
And used these methods to test the connection
http://oauth.rubyforge.org/rdoc/classes/OAuth/Consumer.html
Followed these instructions for implementing the two-legged strategy
Rails two-legged OAuth provider?
But on the consumer side I get
Completed 500 Internal Server Error in 86ms
OAuth::Unauthorized (401 Unauthorized ):
oauth (0.4.7) lib/oauth/consumer.rb:216:in `token_request'
oauth (0.4.7) lib/oauth/consumer.rb:136:in `get_request_token'
...
and on server side
Started POST "/oauth/request_token" for 127.0.0.1 at Sun Jan 06 22:02:08 -0300 2013
Processing by OauthController#request_token as */*
Rendered text template (0.0ms)
Filter chain halted as # <OAuth::Controllers::ApplicationControllerMethods::Filter:0x1111e0e80 #strategies=[:two_legged], #options={:interactive=>false, :strategies=>:two_legged}> rendered or redirected
Completed 401 Unauthorized in 3ms (Views: 2.1ms | ActiveRecord: 0.0ms)
This post seems to point to the same issue
https://github.com/pelle/oauth-plugin/issues/106
I'm using two-legged implementation to allow login to my rails app from my native android app.
This post seems to be related with my problem
Rails Oauth: unable to get request_token, filter chain halted
I don't know where to look or how to get a more detailed log on the server side.
Any help will be appreciated. Thanks!