请教：打开数据库时提示：Object reference not set to an instance of an object.
Exception   Details:   System.NullReferenceException:   Object   reference   not   set   to   an   instance   of   an   object.

Source   Error:  
Line   64:   {
Line   65:   SqlConnection   con=DB.createCon();
Line   66:   con.Open();     //******报错处******
Line   67:   SqlDataAdapter   sda=   new   SqlDataAdapter();
Line   68:   sda.SelectCommand=new   SqlCommand( "select   *   from   employees ",con);
 
Source   File:   d:\c#\asp.net\execise\datagrid.aspx.cs         Line:   66  

Stack   Trace:  
[NullReferenceException:   Object   reference   not   set   to   an   instance   of   an   object.]
      LoadLibraryW(UInt16*   )   +0
      System.EnterpriseServices.Thunk.Security.Init()   +76
      System.EnterpriseServices.Thunk.Security.SuspendImpersonation()   +81
      System.EnterpriseServices.Platform.Initialize()   +503
      System.EnterpriseServices.ResourcePool..ctor(TransactionEndDelegate   cb)   +11
      System.Data.SqlClient.ConnectionPool..ctor(DefaultPoolControl   ctrl)   +797
      System.Data.SqlClient.PoolManager.FindOrCreatePool(DefaultPoolControl   ctrl)   +170
      System.Data.SqlClient.SqlConnectionPoolManager.GetPooledConnection(SqlConnectionString   options,   Boolean&   isInTransaction)   +358
      System.Data.SqlClient.SqlConnection.Open()   +384
      Execise.DataGrid.BinderToDataGrid()   in   d:\c#\asp.net\execise\datagrid.aspx.cs:66
      Execise.DataGrid.Page_Load(Object   sender,   EventArgs   e)   in   d:\c#\asp.net\execise\datagrid.aspx.cs:29
      System.Web.UI.Control.OnLoad(EventArgs   e)   +67
      System.Web.UI.Control.LoadRecursive()   +35
      System.Web.UI.Page.ProcessRequestMain()   +731

 


------解决方案--------------------
DB.createCon(); 出错了没有返回一个连接.
------解决方案--------------------
你电脑是不是装的卡巴6.0.2.621版本，是的话打上 framework1.1的sp1补丁