cask安装报错

[prife]

$ brew install caskroom/cask/brew-cask
==> brew cask install caskroom/cask/brew-cask
Error: Tap caskroom/cask already tapped.

Follow the instructions here:
https://github.com/caskroom/homebrew-cask/blob/master/doc/reporting_bugs/pre_bug_report.md

If this doesn’t fix the problem, please report this bug:
https://github.com/caskroom/homebrew-cask#reporting-bugs

/usr/local/Homebrew/Library/Homebrew/tap.rb:196:in install' /usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/source/untapped_qualified.rb:9:in me?'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/source.rb:28:in block in for_query' /usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/source.rb:26:in each'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/source.rb:26:in find' /usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/source.rb:26:in for_query'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc.rb:57:in load' /usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/install.rb:21:in block in install_casks'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/install.rb:19:in each' /usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/install.rb:19:in install_casks'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/install.rb:10:in run' /usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:110:in run_command'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:149:in process' /usr/local/Homebrew/Library/Homebrew/cask/cmd/brew-cask.rb:8:in <top (required)>'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in require' /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in require'
/usr/local/Homebrew/Library/Homebrew/brew.rb:24:in require?' /usr/local/Homebrew/Library/Homebrew/brew.rb:100:in

'