Retrieving data from ASP.net sql database into amchart

<script type="text/javascript">
    $(document).ready(function () {

        $.ajax({

            type: "POST",
            contentType: "application/json; charset=utf-8",
            url: "Home.aspx/GetData",
            data: "{}",
            dataType: "json",
            success: function (data) {
                debugger
                AmCharts.makeChart("chartdivACHEAD",
            {
                "type": "pie",
                "pathToImages": "http://cdn.amcharts.com/lib/3/images/",
                "balloonText": "[[title]]<br><span style="font-size:14px">[[value]] ([[percents]]%)</span>",
                //"depth3D": 7,
                "labelRadius": 2,

                "labelText": "[[title]]:[[value]]",
                "minRadius": 65,
                "labelsEnabled": true,
                "pullOutOnlyOne": true,
                "titleField": "ac_head",
                "valueField": "AssetCount",

                "fontSize": 9,
                "theme": "default",
                "allLabels": [],
                "balloon": {},
                  "titles": [],
                "dataProvider": [data.d]
            }
        );
            },
            error: function (result) {
                alert("Error");
            }
        });
    });
</script>

public static UserDetails[] GetData()
    {
        DataTable dt = new DataTable();
        List<userdetails> details = new List<userdetails>();
        //string connectionstring = "Data Source=DCS_SERVER;Initial Catalog=DSIM_CLOUD;User ID=sa;Password=sa123;Timeout=200";

        string connectionstring = "Data Source=DCS_SERVER\\SQLEXPRESS;Initial Catalog=NugCloudLiveData;User ID=sa;Password=sa123";
        SqlConnection con = new SqlConnection(connectionstring);
        con.Open();
        SqlCommand comm = new SqlCommand("USP_get_HomePage_count", con);
        comm.CommandType = CommandType.StoredProcedure;
         SqlDataAdapter da = new SqlDataAdapter(comm);
        da.Fill(dt);
        foreach (DataRow dtrow in dt.Rows)
        {
            UserDetails user = new UserDetails();
            user.ac_head = dtrow["ac_head"].ToString();
            user.AssetCount = dtrow["AssetCount"].ToString();
            details.Add(user);
        }

        con.Close();

        // }
        return details.ToArray();

    }
    public class UserDetails
    {

        public string AssetCount { get; set; }
        public string ac_head { get; set; }
    }</userdetails></userdetails></br>