In ckeditor version 4.0 extra plugin not working

i am trying to add extra plugin(colorbutton) in ckeditor 4. i also add color button in plugin folder and also add config.extraPlugins = 'colorbutton'; in config.js.

but apply after this method it gives error and dont show ckeditor. ERROR :- Uncaught TypeError: Cannot read property 'getEditor' of undefined

via Chebli Mohamed