Issue adding omniauth as middleware

All - I'm using Rails 2.3.5 and Devise. I'm trying to integrate Onmiauth into my system. I'm having issues adding it as middleware. The gem is installed as verfied by 'gem list'.

When I try to add 'use OmniAuth::Strategies::Twitter, 'CONSUMER_KEY', 'CONSUMER_SECRET'' to my environment.rb 开发者_JAVA百科I get the following error:

in `activate': can't activate rack (~> 1.1, runtime) for ["oa-core-0.2.0", "omniauth-0.2.0"], already activated rack-1.0.1 for ["actionpack-2.3.5", "rails-2.3.5"] (Gem::LoadError)

I ran rake:middleware and it is not listed as a middleware.

Any ideas?

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This seems really similar to a question I just answered. Rather than writing the answer twice I'll just paste the link to my answer for others to be able to see my best guess as to what's going on. Hopefully this will help with anyone coming across this via Google:

Incompatability between Rails 2.3.5 and Omniauth