Adding panel and list within panel (vbox) just shows "undefined"

[fhdeveloper]

I have the following code to add a list and a panel within another panel:





this.header = new Ext.Panel({
title:"FOO",
html:"<div><b>Hello</b></div>",
layout:'fit'
});

this.list = new Ext.List({
xtype: 'list',
store: this.data,
tpl: this.template,
itemSelector: 'div.none',
singleSelect: true,
grouped: false,
indexBar: false
fullscreen:false
});
// create a list view that has our data, template associated with it
this.items=[this.header,this.list];



This shows the first panel initially (while the ajax request that will fill the list is still completing) but as soon as the request finishes everything is wiped out and all I see is a white screen that says "undefined"
what is going on ??

[evant]

Please provide a drop in test case, it's difficult to say from just that.