Unable to display the button scayt

Hello,
I just put version 4 and I added ckeditor plugin as scayt.
I added in my file Scayt config.js

config.scayt_autoStartup = true
config.scayt_sLang = 'fr_FR';
config.extraPlugins = 'oembed','scayt';
config.toolbar =
    [
        [ 'Find','Replace','-','SelectAll','-','scayt' ]
.....

THE SOLUTION :  config.extraPlugins = 'scayt,oembed';

But I have not the icon in the toolbar.
Thank you for your help