call back issues with twitter integration

Hi,

development env: ruby on rails
oauth: 0.3.5
gem used: twitter_oauth

My code to call twitter is

client = TwitterOAuth::Client.new(
      :consumer_key => Attribute::CONSUMER_KEY,
      :consumer_secret => Attribute::CONSUMER_SECRET)
request_token = client.request_token(:oauth_callback => 'http://abc/
authorization/')
redirect_to request_token.authorize_url

After this, the control goes to
http://twitter.com/oauth/authorize?oauth_token=k*********************

Here the user puts his twitter userid password pressed APPROVE and
gets redirected to
http://twitter.com/oauth/authorize

instead of my call back URL.
Can someone guide why?

Can anyone please help?