ext panel 嵌套问题！~ 子panel 没有显示 求救啊

Ext.onReady(function(){
    var tabs = new Ext.TabPanel({
    xtype:"tabpanel",
activeTab:0,
renderTo: 'tabs1',
width:1064,
height:662,
items:[{
xtype:"panel",
title:"我的面板",
layout:"border",
items:[
{
xtype:"panel",
title:"我的面板",
region:"west",
width:273
},
{
xtype:"panel",
title:"我的面板",
region:"center"
}
]
}]
});

});