VS2008连接SQL2005问题，老连接不上。

VS2008连接SQL2005问题，老连接不上。

自己电脑是服务器和客户机。
SQL我已经设置成了混合登陆模式，用户名和密码都是sa，而且SQL用sa已经登录成功了。
VS里连接用户名和密码我也是用的sa，数据库名也是对的，而且连接成功。
但是当我运行程序的时候就报错，说用户sa登录失败。
“/WebSite1”应用程序中的服务器错误。
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用户 'sa' 登录失败。 
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。 

异常详细信息: System.Data.SqlClient.SqlException: 用户 'sa' 登录失败。

源错误: 


行 55: {
行 56: sqlconn = new SqlConnection(strConn);
行 57: sqlconn.Open();
行 58: 
行 59: sqlcmd = new SqlCommand();
 

源文件: D:\校标1\Solution1\DB\DBHelper.cs 行: 57 

堆栈跟踪: 


[SqlException (0x80131904): 用户 'sa' 登录失败。]
  System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +800131
  System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +186
  System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +1932
  System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK) +33
  System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) +172
  System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) +381
  System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +181
  System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +173
  System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +357
  System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +30
  System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +424
  System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66
  System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +494
  System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +82
  System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +105
  System.Data.SqlClient.SqlConnection.Open() +111
  DB.DBHelper.ExecQuery(String strName, SqlParameter[] sqlparas) in D:\校标1\Solution1\DB\DBHelper.cs:57
  BEM.BEM_Product.Show() in D:\校标1\Solution1\BEM\BEM_Product.cs:18
  _Default.Bind() in d:\校标1\WebSite1\Default.aspx.cs:27
  _Default.Page_Load(Object sender, EventArgs e) in d:\校标1\WebSite1\Default.aspx.cs:20
  System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +15
  System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +33
  System.Web.UI.Control.OnLoad(EventArgs e) +99
  System.Web.UI.Control.LoadRecursive() +47
  System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1436
这是报错信息。我在网上看了好多，都不能解决，麻烦大大们帮下忙。
DB层中的连接字符串是private string strConn = "server=(local);User ID=sa;Password=sa;database=TB001";
Web.config中的是<add key="strConn" value="server=(local);User ID=sa;Password=sa;database=TB001"/>

正确答案如下：

登录数据库的用户名和密码是否正确，配置是否正确
server=(local);User ID=sa;Password=sa;database=master