远程读取数据库问题

using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.Generic;
using System.Linq;
using System.Text;namespace GPSdata0617_Data
{
    class ReadSqlServerData
    {
        private const String connString =
            @"Data Source=121.**.***.***;Initial Catalog=GPSdata;Integrated Security=True";
        private const String SQL =
            @"
SELECT
    TOP 3
    ROW_NUMBER() OVER (ORDER BY GpsDateTime DESC) AS NO
FROM
    GPSdata0617_Data
GROUP BY
    VehicleID
ORDER BY
    GpsDateTime DESC";
        private const String DATATABLE_XML_FILE = "datatable.xml";
        private const String DATATABLE_SCHEMA_XML_FILE = "datatable_schema.xml";
        public void ReadDataToDataSet()
        {
            SqlConnection conn = new SqlConnection(connString);
            SqlDataAdapter adapter = new SqlDataAdapter(SQL, conn);
            DataSet testDataSet = new DataSet();
            adapter.Fill(testDataSet, "result_data");
            conn.Close();
            foreach (DataRow testRow in testDataSet.Tables["result_data"].Rows)
            {
                Console.WriteLine("NO:{0}   ",
                    testRow["NO"]
                    );
            }
            testDataSet.Tables["result_data"].WriteXmlSchema(DATATABLE_SCHEMA_XML_FILE);
            testDataSet.Tables["result_data"].WriteXml(DATATABLE_XML_FILE);
            DataTable newDt = new DataTable();
            newDt.ReadXmlSchema(DATATABLE_SCHEMA_XML_FILE);
            newDt.ReadXml(DATATABLE_XML_FILE);
            foreach (DataRow testRow in newDt.Rows)
            {
                Console.WriteLine("NO:{0}   ",
                    testRow["NO"]
                    );
            }
        }
        public void ReadDataByReader()
        {
            SqlConnection conn = new SqlConnection(connString);
            conn.Open();
            SqlCommand testCommand = conn.CreateCommand();
            testCommand.CommandText = SQL;
            SqlDataReader testReader = testCommand.ExecuteReader();
            while (testReader.Read())
            {
                Console.WriteLine("NO:{0}   ",
                    testReader["NO"]);
            }
            testReader.Close();
            conn.Close();
        }
    }
}
程序报错了，但是不知道为什么，求助大神们帮帮忙看一下