beautiful-docs installation problem

[bilalyasar]

I am trying to install bfdocs from the master source.
after npm install -g, when i execute command bfdocs, i am getting following error:

module.js:338
    throw err;
          ^
Error: Cannot find module '../lib/command.js'
    at Function.Module._resolveFilename (module.js:336:15)
    at Function.Module._load (module.js:278:25)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)
    at Object.<anonymous> (/usr/local/lib/node_modules/beautiful-docs/bin/bfdocs:2:1)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:501:10)

any idea about this problem?