web服务问题：用户代码未处理 System.ArgumentException 不支持关键字'source'

代码如下：
newspublish.asmx.cs

using System;
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Data;
using System.Data.SqlClient;

/// <summary>
/// NewsPublish 的摘要说明
/// </summary>
[WebService(Namespace = "http://localhost/news", Description = "该系统提供了10个服务。")]//此出namespace要写成该服务在IIS上网址，否则会出错“ 未能创建类型“NewsPublish”
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class NewsPublish : System.Web.Services.WebService
{
     public string ConnectionString = "Source=ZXB;Initial Catalog=news;Integrated Security=True";
    //SqlConnection conn = new SqlConnection(ConnectionString);

    public NewsPublish ()
    {
    }
    [WebMethod(Description = "该服务用于验证用户身份，返回值表示验证是否通过。")]
    public bool VerifyUser(string username, string password)
    {

        SqlConnection conn = new SqlConnection();
        conn.ConnectionString = ConnectionString;
        bool bRet = false;
        SqlCommand cmd = new SqlCommand("VerifyUser", conn);
        cmd.CommandType = CommandType.StoredProcedure;

        cmd.Parameters.Add(new SqlParameter("@username", SqlDbType.VarChar,50));
        cmd.Parameters["@username"].Value = username;
        cmd.Parameters.Add(new SqlParameter("@password", SqlDbType.VarChar, 50));
        cmd.Parameters["@password"].Value = password;

        cmd.Parameters.Add(new SqlParameter("@return", SqlDbType.Int));
        cmd.Parameters["@return"].Direction = ParameterDirection.ReturnValue;

        try
        {
            conn.Open();
            cmd.ExecuteNonQuery();
            int ret = (int)cmd.Parameters["@return"].Value;
            if (ret == 0)
            {
                bRet = true;
            }
        }
        catch { }
        finally
        { conn.Close(); }
        return bRet;
     }

在aspx。cs文件里调用，就出现了这个错误。

忘高手提点提点 --------------------编程问答-------------------- 补充一下：conn.ConnectionString = ConnectionString;是显示这句出错。 --------------------编程问答-------------------- public   string   ConnectionString   =   "Source=ZXB;......";
这里是Data Source=ZXB --------------------编程问答--------------------   public   string   ConnectionString   =   "Data Source=ZXB;Initial   Catalog=news;Integrated   Security=True "; --------------------编程问答-------------------- 改为server试试 --------------------编程问答-------------------- 检查连接字符窜。。。

补充：.NET技术 ,  ASP.NET