我正在尝试使用Ruby on Rails安装active_admin。每次我输入：
rails g active_admin:install
我收到如下错误消息：
用户/ audreyjoanne / .rbenv /版本/ 2.4.0 / LIB /红宝石/宝石/ 2.4.0 /宝石/的ActiveSupport-5.0.4 / LIB / active_support /偏转器/ methods.rb：268：在 ＆＃39; const_get＆＃39;：未初始化的常量AdminUser（NameError）来自 /Users/audreyjoanne/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/activesupport-5.0.4/lib/active_support/inflector/methods.rb:268:in ＆＃39;阻止constantize＆＃39;从 /Users/audreyjoanne/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/activesupport-5.0.4/lib/active_support/inflector/methods.rb:266:in ＆＃39;每个＆＃39;
我该如何解决这个问题？