activeItem not updating panel

[bstras21]

Shouldn't this code go the second panel? It's not

var viewport = Ext.create('Ext.Panel', {
            fullscreen: true,
            id:'mainViewport',
            layout: 'card',
            activeItem: 1,
            items: [{
                 xtype: 'LoginForm'
                 },{
                 xtype: 'MainPunchApp'
            }],
            
        });