ruby on rails 安装问题 devkit始终无法识别rubygems?

Question

根据教程一步一步安装，甚至手动安装了rubygems但是ruby dk.rb install 这一步中始终找不到rubygems请问要怎么办？提示：[INFO] Skipping existing gem override for 'd:/Ruby200-x64'[WARN] Skipping existing DevKit helper library for 'd:/Ruby200-x64'[ERROR] Unable to find RubyGems in site_ruby or core Ruby. Pleaseinstall RubyGems and rerun 'ruby dk.rb install'.但是输入gem -v,又能得到版本号D:\devkit1>gem -v2.1.7请问是什么地方出了问题？