跪求解决啊 数据库连接的问题
我的数据库可以打开，也可以查看里面的数据库。但是我用VS2010写的程序，却无法打开数据库，总是说登录失败。
 string strcon = @"Server=(local)\\SQLExpress;Initial Catalog=MBOOK;Integrated security =true";
//@"Data Source=.;Initial Catalog=XJGL;Integrated security =SSPI ";china-18b9ac675\SQL2008User ID=sa;Password=123456


  //@"Date Source =china-18b9ac675\SQL2008;Initial Catalog=XJGL;Integrated Security=SSPI";
这些常用的语句我试过了。现在用的是
 string strcon = @"Server=(local)\\SQLExpress;Initial Catalog=MBOOK;Integrated security =true";

出现的错误是


“/”应用程序中的服务器错误。
--------------------------------------------

实例失败。 
说明: 执行当前 Web 请求期间，出现未经处理的异常。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.InvalidOperationException: 实例失败。

源错误: 


行 32: cmd.Parameters.Add("@account", SqlDbType.Char, 20).Value = TextBox3.Text.Trim();
行 33: cmd.Parameters.Add("@password", SqlDbType.Char, 20).Value = TextBox4.Text.Trim();
行 34: conn.Open();
行 35: cmd.ExecuteNonQuery();
行 36: 
 

源文件: F:\360data\重要数据\我的文档\Visual Studio 2010\Projects\ADO\ADO\Default.aspx.cs 行: 34 

堆栈跟踪: 


[InvalidOperationException: 实例失败。]
  System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity) +5062694
  System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, SqlConnection owningObject) +129
  System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, TimeoutTimer timeout) +164
  System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, TimeoutTimer timeout, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +195
  System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +232
  System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +185
  System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +33
  System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +524
  System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66
  System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +479
  System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +108
  System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +126
  System.Data.SqlClient.SqlConnection.Open() +125
  ADO._Default.Button2_Click(Object sender, EventArgs e) in F:\360data\重要数据\我的文档\Visual Studio 2010\Projects\ADO\ADO\Default.aspx.cs:34
  System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
  System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112