js从后台无法取值问题

<script type="text/javascript">
$(function () {
var chart;
$(document).ready(function () {
chart = new Highcharts.Chart({
chart: {
renderTo: 'container',
type: 'line',
marginRight: 130,
marginBottom: 25
},
title: {
text: '新增用户趋势图',
x: -20 //center
},
subtitle: {
text: 'Source: tourol.cn',
x: -20
},
xAxis: {
categories: <%= json_dates %>
},
yAxis: {
title: {
text: '人数'
},
plotLines: [{
value: 0,
width: 1,
color: '#808080'
}]
},
tooltip: {
formatter: function () {
return '<b>' + this.x + '</b><br/>' +
'新增加人数 ' + this.y;
}
},
legend: {
layout: 'vertical',
align: 'right',
verticalAlign: 'top',
x: -10,
y: 100,
borderWidth: 0
},
series: [{
name: '新增人数',
data: <%= json_addusers %>
}]
});
});

});
$(function () {
$(".index_tap_item>a").click(function () {
$(".nav-stacked>li").each(function () {
$(this).removeClass('active');
$("#liuserstatics").addClass('active');
});
$(".tab-pane").each(function () {
$(this).removeClass('active');
$("#userstatics").addClass('active');
});
});
});
</script>

public partial class statics_Default : System.Web.UI.Page
{
public string json_addusers = string.Empty;
public string json_dates = string.Empty;

protected void Page_Load(object sender, EventArgs e)
{
getData();
}

private void getData()
{
System.Data.DataTable datas = DBUtility.DBExecuteUtil.querySqlTable(
" SELECT COUNT(*) addusers,CONVERT(varchar(100), [RegistDate], 23) dates  FROM [FenxCloudZj].[dbo].[tourol_B2CUser]  group by CONVERT(varchar(100), [RegistDate], 23)");
string json1 = "[";
string json2 = "[";
for (int i = (datas.Rows.Count > 10 ? 10 : datas.Rows.Count); i > 0; i--)
{
json1 += datas.Rows[i]["addusers"] + ",";
json2 += "\"" + datas.Rows[i]["dates"] + "\",";
}
json1 = json1.TrimEnd(',');
json1 += "]";
json_addusers = json1;
json2 = json2.TrimEnd(',');
json2 += "]";
json_dates = json2;
}
}