求大神帮我看看为什么连接SQL数据库不成功？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Data.SqlClient;

/// <summary>
///
/// </summary>
public static class db
{
    public static SqlConnection getConn()
    {
        SqlConnection conn = new SqlConnection();
        conn.ConnectionString = "SERVER=XGG\SQL2008;UID=sa; PWD=123; DATABASE=subscriber";
        conn.Open();//运行后每次都是在这报错
        return conn;
    }
    public static DataSet getDataSet(string SQL)
    {
        SqlDataAdapter da = new SqlDataAdapter(SQL, getConn());
        DataSet ds = new DataSet();
        da.Fill(ds);
        return ds;
    }
}