REXML error for riddle

[mohitnegi]

I Am including REXML in my application_controller so by default all the controller will have that.

Now if i am calling any method which calls a model in which i have defined my sphinx index, An error is thrown

undefined method `default_external' for REXML::Encoding:Module

Stack trace for the error

NoMethodError (undefined method `default_external' for REXML::Encoding:Module):

  riddle (1.4.0) lib/riddle.rb:15:in `encode'

  riddle (1.4.0) lib/riddle/client/response.rb:20:in `next'

  riddle (1.4.0) lib/riddle/client/response.rb:51:in `next_array'

  riddle (1.4.0) lib/riddle/client/response.rb:50:in `times'

  riddle (1.4.0) lib/riddle/client/response.rb:50:in `next_array'

  riddle (1.4.0) lib/riddle/client.rb:246:in `run'

  riddle (1.4.0) lib/riddle/client.rb:228:in `collect'

  riddle (1.4.0) lib/riddle/client.rb:228:in `run'

  riddle (1.4.0) lib/riddle/client.rb:338:in `query'

  /opt/ruby-enterprise-1.8.7-2011.03/lib/ruby/gems/1.8/gems/thinking-sphinx-1.4.7/lib/thinking_sphinx/search.rb:402:in `populate'

  /opt/ruby-enterprise-1.8.7-2011.03/lib/ruby/gems/1.8/gems/thinking-sphinx-1.4.7/lib/thinking_sphinx/search.rb:401:in `populate'

  /opt/ruby-enterprise-1.8.7-2011.03/lib/ruby/gems/1.8/gems/thinking-sphinx-1.4.7/lib/thinking_sphinx/search.rb:556:in `call'

  /opt/ruby-enterprise-1.8.7-2011.03/lib/ruby/gems/1.8/gems/thinking-sphinx-1.4.7/lib/thinking_sphinx/search.rb:556:in `retry_on_stale_index'

  /opt/ruby-enterprise-1.8.7-2011.03/lib/ruby/gems/1.8/gems/thinking-sphinx-1.4.7/lib/thinking_sphinx/search.rb:398:in `populate'

  /opt/ruby-enterprise-1.8.7-2011.03/lib/ruby/gems/1.8/gems/thinking-sphinx-1.4.7/lib/thinking_sphinx/search.rb:167:in `method_missing'

  app/models/shortlist_criteria_rules.rb:125:in `do_search'

  app/models/shortlist_criteria_rules.rb:30:in `do_search'

  app/controllers/shortlist_criteria_rules_controller.rb:56:in `index'

I guess something is overridden in riddle!!!! but not able to fix tht... any help !!!!!!