Opening new Window in Tab (CommonJS Style..?)

Hi,

So i am trying to create a tabbed app:

Tab1 > Window 1 > Window 2 > Window 3

Tab 2 would be the same.

I have followed the template from Appcelerator Developer relations example: https://github.com/appcelerator-developer-relations/Template.Tabbed

Once I have the first window open, I want the button click to open another window.

The example is:

function ApplicationWindow(title) {
var self = Ti.UI.createWindow({
title:title,
backgroundColor:'white'
});
 
var button = Ti.UI.createButton({
height:44,
width:200,
title:L('openWindow'),
top:20
});
self.add(button);
 
button.addEventListener('click', function() {
//containingTab attribute must be set by parent tab group on
//the window for this work
self.containingTab.open(Ti.UI.createWindow({
title: L('newWindow'),
backgroundColor: 'white'
}));

This just creates and opens a New window. I want to open a window that is in another file win2.JS:

This is the code in win2.JS:

function Win2() {
    var nextWin = Ti.UI.createWindow({
        title : title,
        backgroundColor : 'white'
    });
    return nextWin;
};
 
module.exports = Win2;

This is my code to call this from the original one:

button.addEventListener('click', function() {
testWin = require('win2');
self.containingTab.open(testWin);

My attempts so far have resulted in [WARN] Exception in event callback. { on iOS.....

Not sure where it is going wrong or what to change in the code...