Hi everyone. I am new in Laravel 5 here.

I faced some difficulty to compile SASS file by using Gulp.

I watch the screencast video from here.
Laravel Elixir Screencast

This is my code:

elixir(function(mix) {
    mix.sass('materialize.scss')
    .routes()
    .events()
    .phpUnit();
});

This is the error message.

D:\XAMPP\htdocs\membership-system\gulpfile.js:16
    .routes()
     ^
TypeError: undefined is not a function
    at D:\XAMPP\htdocs\membership-system\gulpfile.js:16:6
    at Elixir (D:\XAMPP\htdocs\membership-system\node_modules\laravel-elixir\ind
ex.js:3:5)
    at Object.<anonymous> (D:\XAMPP\htdocs\membership-system\gulpfile.js:14:1)
    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 Module.require (module.js:365:17)
    at require (module.js:384:17)
    at Liftoff.handleArguments (C:\Users\Wee Hong\AppData\Roaming\npm\node_modul
es\gulp\bin\gulp.js:116:3)

If I remove routes(), events() and phpUnit(), it manages to compile successfully. But it does not appear in my public/css/

Please give me some advises how to overcome this issue. Thank you and please excuse my poor English.