尝试使用WordPress堆栈设置Capistrano时出现NoMethodError

我正试着跑

cap staging deploy:setup

我得到了这个错误。我对terminal不是很熟悉，我是按照本教程来设置的-

我一直在寻找解决方案，并尝试解决这个问题。而且输入将是有帮助的

cap aborted!
NoMethodError: undefined method `instance' for Capistrano::Configuration:Class
/Library/Ruby/Gems/2.0.0/gems/railsless-deploy-1.1.3/lib/railsless-deploy.rb:1:in `<top (required)>'
/Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:128:in `require'
/Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:128:in `rescue in require'
/Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:39:in `require'
/Users/kylebebeau/websites/theinitgroup/Capfile:2:in `<top (required)>'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/rake_module.rb:28:in `load'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/rake_module.rb:28:in `load_rakefile'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/application.rb:687:in `raw_load_rakefile'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/application.rb:94:in `block in load_rakefile'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/application.rb:176:in `standard_exception_handling'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/application.rb:93:in `load_rakefile'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/application.rb:77:in `block in run'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/application.rb:176:in `standard_exception_handling'
/Library/Ruby/Gems/2.0.0/gems/rake-10.3.2/lib/rake/application.rb:75:in `run'
/Library/Ruby/Gems/2.0.0/gems/capistrano-3.2.1/lib/capistrano/application.rb:15:in `run'
/Library/Ruby/Gems/2.0.0/gems/capistrano-3.2.1/bin/cap:3:in `<top (required)>'
/usr/bin/cap:23:in `load'
/usr/bin/cap:23:in `<main>'