How to fix Routing in Marionette when using Browserify - backbone.js

Question

I have a Marionette project and I try to make it work with Browserify.
My app.js:
var $ = require('jquery');
var Backbone = require('backbone');
Backbone.$ = $;
Marionette = require('backbone.marionette');
var Controller = require("./controller");
var Router = require("./routes");
var App = new Marionette.Application();
...
App.addRegions({
header: "#header_region",
side_menu: "#side_menu_region",
main: "#main_region",
footer: "#footer_region"
});
...
var controller = new Controller({});
App.addInitializer(function(options){
...
var router = new Router({
controller : controller
});
});
App.on("start", function(){
Backbone.history.start();
});
App.start({});
module.exports = App;
My controller.js:
var headerView = require('./header/view');
var sideMenuView = require('./side_menu/view');
module.exports = function() {
var Controller = Marionette.Controller.extend({
showHome: function(){
var header_view = new headerView();
App.header.show(header_view);
var side_menu_view = new sideMenuView();
App.side_menu.show(side_menu_view);
}
});
return Controller;
}
My routes.js:
module.exports = function() {
var Route = Marionette.AppRouter.extend({
appRoutes: {
'': 'showHome'
}
});
return Route;
}
My browserify command:
browserify app.js -o bundle.js
For some reason, I can't get into my showHome function inside the controller.
So when I go to my site, I get an empty page without any errors in the console.
Does anybody know what am I missing?
Thanks, Alex