请问 extjs中的 radio 为啥不显示 大家看看吧

Question

  <script>
Ext.onReady(function(){
var f = new Ext.form.FormPanel({
title:"面板",
width:300,
autoHeight:true,
frame:true,
renderTo:"d",
labelWidth:65,
labelAlign:"right",
defaultType:"textfield",
items:[{
name:"userName",
fieldLabel:"用户名",
width:200
},{
name:"password1",
fieldLabel:"密码",
inputValue:"password",
width:200
},{
name:"sexGroup",
fieldLabel:"性别",
xtype:"radiogroup",
width:100,
items:[
{
name:"sex",
xtype:"radio",
boxLabel:"男",
inputValue:"男",
checked:true
},
{
name:"sex",
xtype:"radio",
boxLabel:"女",
inputValue:"女"
}
]
}],
})
})
</script>