TinyMCE submenu icon (Wordpress)

TinyMCE submenu icon (Wordpress)

I´m create a menu with TinyMCE on Wordpress post page (create a css class
that puts a backgorund-image in that menu). This same menu contains a
submenu, that contains the same class applied for icon, but the does not
appear.
Anyone can help, please...
below the code that I have
var sub = m.addMenu({
title: 'Icons',
icon: 'tablet'
});
sub.add({
title : 'Tablet',
icon: 'tablet',
onclick : function() {
tinyMCE.activeEditor.selection.setContent('[icon img="tablet"]');
}
});
sub.addSeparator();