我正在尝试安装passenger-install-apache2-module，但收到此错误：
[root@devserver redmine]# passenger-install-apache2-module
/usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/yaml.rb:56:in `<top (required)>':
It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.
/usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/resolver.rb:287:in `resolve': Could not find gem 'rails (= 3.2.6) ruby' in the gems available on this machine. (Bundler::GemNotFound)
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/resolver.rb:161:in `start'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/resolver.rb:128:in `block in resolve'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/resolver.rb:127:in `catch'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/resolver.rb:127:in `resolve'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/definition.rb:192:in `resolve'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/definition.rb:127:in `specs'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.4/lib/bundler/environment.rb:27:in `specs'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.3/lib/rubygems-bundler/noexec.rb:41:in `candidate?'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.3/lib/rubygems-bundler/noexec.rb:60:in `setup'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.3/lib/rubygems-bundler/noexec.rb:75:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
from /usr/local/rvm/gems/ruby-1.9.3-p194/bin/ruby_noexec_wrapper:9:in `<main>'
我想念什么？