Getting 'Could not find gem 'dbyll' in any of the gem sources listed in your Gemfile or available on this machine.'

[WenChao Kong]

Hi
Thanks for the theme, I'm really new to using Jekyll,
I run 'bundle install' under this project repo firstly.
and I have change the Gemfile under my site folder to add this line

gem "dbyll"

and I run 'bundle install'
it gives me this error.

Thanks.