我正在尝试运行 Ruby on Rails 项目。我安装了 RVM，将 Ruby 设置为 1.8.7 版本，并且让所有东西都启动并运行，除非我尝试运行rackup我得到：
/Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler/spec_set.rb:92:in `materialize': Could not find backports-3.3.2 in any of the sources (Bundler::GemNotFound)
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler/spec_set.rb:85:in `map!'
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler/spec_set.rb:85:in `materialize'
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler/definition.rb:114:in `specs'
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler/definition.rb:159:in `specs_for'
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler/runtime.rb:13:in `setup'
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler.rb:127:in `setup'
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.3.5/lib/bundler.rb:132:in `require'
from /Users/afrieden/Downloads/neo_visual_search-master/neovs_app.rb:2
from /Users/afrieden/.rvm/rubies/ruby-1.8.7-p374/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
from /Users/afrieden/.rvm/rubies/ruby-1.8.7-p374/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'
from /Users/afrieden/Downloads/neo_visual_search-master/config.ru:4
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/rack-1.5.2/lib/rack/builder.rb:55:in `instance_eval'
from /Users/afrieden/.rvm/gems/ruby-1.8.7-p374/gems/rack-1.5.2/lib/rack/builder.rb:55:in `initialize'
from /Users/afrieden/Downloads/neo_visual_search-master/config.ru:0:in `new'
from /Users/afrieden/Downloads/neo_visual_search-master/config.ru:0
我试过gem install Bundler了，但它刚刚重新安装，我得到了同样的错误。
有没有人见过这个问题？谢谢！