How to set activeTab upon app load?

Am having problems with setting the active tab of my application upon load. I am trying to use tabGroup.activeTab = tabGroup.getTabs[3]; whereas the '3' is the 4th tab in my tabGroup. '0' is the first tab I believe.

app.js:

// Do it this way as to not pollute the global namespace
var sampleapplication = {}; // define app's namespace
 
Ti.include('ui.js');
 
// Use custom UI constructors to build the app's UI
sampleapplication.container = sampleapplication.ui.createApplicationContainer();
 
// open tab group
setTimeout(function() {
    sampleapplication.container.open({
        transition:Titanium.UI.iPhone.AnimationStyle.FLIP_FROM_RIGHT
    });
}, 0 //time to wait
);

ui.js:

(function(){
    sampleapplication.ui = {};
 
    sampleapplication.ui.createApplicationContainer = function() {
        var tabGroup = Titanium.UI.createTabGroup();
 
        Ti.include('includes/win1.js');
        var win1Tab = Titanium.UI.createTab({
            window:win1
        });
 
        Ti.include('includes/win2.js');
        var win2Tab = Titanium.UI.createTab({
            window:win2
        });
 
        Ti.include('includes/win3.js');
        var win3Tab = Titanium.UI.createTab({
            window:win3
        });
 
        Ti.include('includes/win4.js');
        var win4Tab = Titanium.UI.createTab({
            window:win4
        });
 
        // add tabs
        tabGroup.addTab(win1Tab);
        tabGroup.addTab(win2Tab);
        tabGroup.addTab(win3Tab);
        tabGroup.addTab(win4Tab);
 
        return tabGroup;
 
        // set active tab to the 4th (win4) tab
        tabGroup.activeTab = tabGroup.getTabs[3]; //or 'tabGroup.activeTab = tabGroup.tabs[3];'
    };
})();

Set the activeTab property before you open() the tabGroup.

to set it before open:

tabGroup.activeTab = 3;

After opened:

tabGroup.setActiveTab(3);

Remember "tabGroup" is actually the variable you used to create the tabGroup.