Trying to get a tabgroup based app working

app.js

require('modules/monkeypatch').monkeypatch(this);
(function() {
	Titanium.UI.setBackgroundColor('#fff');
	require('modules/core').loadTabGroup('LoginTabGroup');
})();

core.js

var activeTabGroup = null;

/**
 * Loads a tab group
 * @param {String} name Name of tabGroup
 * @param {Object} params Additional parameters
 */
exports.loadTabGroup = function(name, params) {
	activeTabGroup = require('modules/ui/' + name);
	activeTabGroup.load(exports, params);
};

/**
 * Returns the active tabGroup module
 * @return {Object} active tabGroup
 */
exports.activeTabGroup = function() {	
	return activeTabGroup;
};

/**
 * Returns the active tab of the active tabGroup module 
 * @return {Object} active tab
 */
exports.activeTab = function() {
	return activeTabGroup.activeTab();
};

Tab.js

/**
 * Loads the Login tab
 * @param {Object} instance of the core module
 * @param {Object} params Additional parameters
 */
exports.load = function(app, params) {
	var tab = Ti.UI.createTab({
		title: 'Title'
	});
	app.activeTabGroup().add(tab);
        app.activeTabGroup().activeTab(tab);
	require('modules/ui/Window').load(app, params);
};

tabGroup.js

var tabGroup = Ti.UI.createTabGroup();

/**
 * Loads the Login tabGroup
 * @param {Object} instance of the core module
 * @param {Object} params Additional parameters
 */
exports.load = function(app, params) {
	require('modules/ui/Tab').load(app, params);
	tabGroup.open();
};

/**
 * Returns the active tab of the Login tabGroup
 * @return {Object} active tab
 */
exports.activeTab = function(tab) {
	if (tab) {
		tabGroup.setActiveTab(tab);
	} else {
		return tabGroup.activeTab;
	}
};

/**
 * Adds a tab to the Login tabGroup
 * @param {Object} tab
 */
exports.add = function(tab) {
	tabGroup.add(tab);
};

Window.js

**
 * Loads the Login Window
 * @param {Object} instance of the core module
 * @param {Object} params Additional parameters
 */
exports.load = function(app, params) {
	var win = Ti.UI.createWindow({
		title: "Window",
		tabBarHidden: true
	});
        app.activeTabGroup().activeTab().add(loginWin);
};