Fórum Uso do Membership.GetUser com o Login Control #7562

Olá Pessoal.
Já utilizo o comando "Membership.GetUser" abaixo normalmente em outras telas, com o VS 2008.
Entretanto estou precisando utilizá-lo numa tela com o ASP.NET Login Control.
E ao utilizálo nessa tela da a mensagem de erro abaixo "Object reference not set to an instance of an object". Grato
Sidney ---------------------------------------------- using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls; public partial class login : System.Web.UI.Page
{
    MembershipUser u;
    protected void Page_Load(object sender, EventArgs e)
    {     }
    protected void LoginButton_Click(object sender, EventArgs e)
    {
        u = Membership.GetUser(User.Identity.Name);
        Session.RemoveAll();
        Session["%UsuarioNome"] = u.UserName;
    }
} ----------------------------------------------   Server Error in '/tpm2.0' Application.
-------------------------------------------------------------------------------- Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. Source Error:
Line 21:         u = Membership.GetUser(User.Identity.Name);
Line 22:         Session.RemoveAll();
Line 23:         Session["%UsuarioNome"] = u.UserName;
Line 24:     }
Line 25: }
  Source File: c:\Desenvolvimento VS2008\tpm\tpm2.0\login.aspx.cs    Line: 23 Stack Trace:
[NullReferenceException: Object reference not set to an instance of an object.]
   login.LoginButton_Click(Object sender, EventArgs e) in c:\Desenvolvimento VS2008\tpm\tpm2.0\login.aspx.cs:23
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +105
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +107
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +7
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +11
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1746