Rails 3 app breaks Rails 2 app

I've got a VPS with Apache/mod_rails installed. I had a virtual host set up for redmine (rails 2 app) that was working just fine. Then I set up a virtual host with my own rails 3 app and got it working, but now when I try to access redmine, passenger throws up the error: can't activate activesupport (= 3.0.9, runtime) for ["railties-3.0.9"], already activated activesupport-2.3.11 for ["rails-2.3.11"]

How do I fix this to get both apps working?