How do I fix my Serialization to produce correct JSON

Json2 = {ID:someID, datetime:somedatetime, col1:somecol1, col2:somecol2, col3:somecol3};

[System.Web.Services.WebMethod]
public static string GetJSONdata(string ID)
{
    DataSet ds = new DataSet();
    DataTable dt = new DataTable();
    string connStr = ConfigurationManager.ConnectionStrings["jsonobject"].ConnectionString;
    string cmdStr = "SELECT ([idd],[datetime],[col1],[col2],[col3]) FROM [jsondata] WHERE [idd]=@idd;";
    try
    {
        using (SqlConnection conn = new SqlConnection(connStr))
        {
            using (SqlCommand cmd = new SqlCommand(cmdStr, conn))
            {
                conn.Open();
                cmd.Parameters.AddWithValue("@idd", ID);
                using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                    da.Fill(ds);
                    dt = ds.Tables[0];
                }
            }
        }
    }
    catch (Exception ex)
    {

    }
    System.Web.Script.Serialization.JavaScriptSerializer serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
    List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
    Dictionary<string, object> row;
    foreach (DataRow dr in dt.Rows)
    {
        row = new Dictionary<string, object>();
        foreach (DataColumn col in dt.Columns)
        {
            row.Add(col.ColumnName, dr[col]);
        }
        rows.Add(row);
    }
    var json2 = serializer.Serialize(rows);
    return json2;
}