Redmine

I can run redmine via webrick successfully, however with apache I get the following error:
/var/www/vhosts/redmine/public/../config/../vendor/rails/railties/lib/initializer.rb:271:in `require_frameworks': Could not find rack (~> 1.1.0) amongst [] (RuntimeError)

here's gem list:
actionmailer (2.3.14)
actionpack (2.3.14)
activerecord (2.3.14)
activeresource (2.3.14)
activesupport (2.3.14)
bundler (1.0.22)
coderay (0.9.8)
daemon_controller (1.0.0)
fastthread (1.0.7)
hoe (2.15.0)
i18n (0.4.2)
mysql (2.8.1)
passenger (3.0.11)
rack (1.1.3)
rails (2.3.14)
rake (0.9.2, 0.8.3)
RedCloth (4.2.9)
rubygems-update (1.7.2, 1.7.0)
rubytree (0.5.2)

what's wrong?
thanks.