这是我的代码，但是date显示出来是Nan-Nan-Nan请问该怎么办= =

function FormatDate (strTime) {
    var date = new Date(strTime);
    return date.getFullYear()+"-"+(date.getMonth()+1)+"-"+date.getDate();
}

function rightModify(qfgRightId){
	$.ajax({
		type: 'POST',
		url: "${ctx}/designRequire/rightmodify",
		data: {"qfgRightId":qfgRightId},
		error: function(XMLHttpRequest, textStatus, errorThrown) {
			alert(XMLHttpRequest.status+""+XMLHttpRequest.readyState+""+textStatus);
		},
		success: function(data){
			var date=FormatDate(data.rightInfo.dtExpireDate);
			alert(date);
			if(data.ok == true){
				$("#nmSqbId").val(data.rightInfo.nmSqbId);
				$("#qfgRightId").val(data.rightInfo.qfgRightId);
				$("#stRightNum").val(data.rightInfo.stRightNum);
				$("#stIssueOrgan").val(data.rightInfo.stIssueOrgan);
				$("#dtExpireDate").val(date);
				$("#nmLandArea1").val(data.rightInfo.nmLandArea);
				$("#black_bg").show();
				$(".black_bg_table").show();
			}else{
				alert("数据出错！请稍后再试。");
			}
		}
	});
}