"cask" description raises an error

In my environment (2012 MBP Retina 15' and OSX Mavericks), 
"cask" description in Brewfile always raises an error and I cannot install any casks.

In Brewfile:  
> cask 'google-chrome'

and exec "brewdle install", I got below error:
> Error: This command requires a cask's name
> error: Unable to install google-chrome. Homebrew-cask is not currently installed on your system. Use --trace to view backtrace

It seems to me that latest Homebrew-cask cannot accept 'brew cask info' command without an cask's name.
I changed it to just "brew cask" command.