Jquery UI Datepicker altField输入无效

Question

我有两个带有datepicker的输入，我需要第一个datepicker可以初始化另一个，这适用于altField，但第二个输入的日期选择器不再起作用。我用这些数据做了一个例子：

https://jsfiddle.net/5njLoxd5/

<input type="text" id="lightBillingStartdate" /><br/>
<input type="text" id="lightBillingFinishDate" /><br/>

$( "#lightBillingStartdate" ).datepicker({
    altField: "#lightBillingFinishDate",
    altFormat: "dd/mm/yy",
    dateFormat: "dd/mm/yy",
    maxDate: 0,
    onSelect: function(selected) {
        $("#lightBillingFinishDate").datepicker("option","minDate", selected);
    }        
});

$( "#lightBillingFinishDate" ).datepicker({
    dateFormat: "dd/mm/yy",
    maxDate: 0,
    onSelect: function(selected) {
                $("#lightBillingStartdate").datepicker("option","maxDate", selected);
    } 
});