Customise tabGroup / tabs

Hi guys, I'm a Indie customer & am having problems trying to style the tabs/tabGroups. I cannot seem to change the background-image for either a tab or more importantly tabGroup. Here is the code:

Titanium.UI.setBackgroundColor('#fff');
 
var tabGroup = Titanium.UI.createTabGroup({
    backgroundImage:'tabGroupBg.png'
});
 
var win1 = Titanium.UI.createWindow({  
    title:'Tab 1',
    //backgroundColor:'#fff',
    backgroundImage:'tabGroupBg.png'
});
 
var tab1 = Titanium.UI.createTab({  
    icon:'KS_nav_views.png',
    title:'Tab one',
    //backgroundColor: '#ccc',
    backgroundImage:'tabGroupBg.png',
    window:win1
});
 
tabGroup.addTab(tab1);  
tabGroup.open();

As you can see the win.backgroundImage is working, although its the same image being used the tab/tabGroup.backgroundImage do not show. My aim is to have 4/5 tabs with a background across them all. Do I have to set the opacity of the tabs? Any help greatly appreciated guys & dolls :)