我已经在OSX上安装了乘客首选项窗格，但每当我尝试运行应用程序时，我都会收到500内部错误。查看日志会给我以下错误：
/usr/local/lib/ruby/gems/1.8/gems/passenger-2.2.5/lib/phusion_passenger/utils.rb:25:in `require': no such file to load -- rubygems (LoadError)
from /usr/local/lib/ruby/gems/1.8/gems/passenger-2.2.5/lib/phusion_passenger/utils.rb:25
from /usr/local/lib/ruby/gems/1.8/gems/passenger-2.2.5/bin/passenger-spawn-server:53:in `require'
from /usr/local/lib/ruby/gems/1.8/gems/passenger-2.2.5/bin/passenger-spawn-server:53
[ pid=403 file=ext/apache2/Hooks.cpp:725 time=2009-11-15 23:33:38.110 ]:
Unexpected error in mod_passenger: Cannot spawn application '/Users/waynemolina/Projects/sandbox/rack-hello-world': The spawn server has exited unexpectedly.
Backtrace:
in 'virtual boost::shared_ptr Passenger::ApplicationPoolServer::Client::get(const Passenger::PoolOptions&)' (ApplicationPoolServer.h:471)
in 'int Hooks::handleRequest(request_rec*)' (Hooks.cpp:521)
由于rubygems在其他地方都有效，我只能假设这个错误是因为Passenger正在寻找Rubygems的错误位置。我手动安装了Rubygems，根据/usr/local/bin/gem，它位于which gem。但是，whereis gem会返回/usr/bin/gem。我不知道我需要采取哪些措施来解决这个问题，而不仅仅是重新安装OSX并升级内置的RubyGems安装而不是自己安装它。