Using ASP.NET Web Admin tool, i created 5 users and assigned them to different roles, but when i try to user Roles.IsUserInRole, it doesn't work, please take a look here:

protected void Login1_Authenticate(object sender, AuthenticateEventArgs e)
    {
        string username = Login1.UserName;
        string password = Login1.Password;

        if (!IsPostBack)
        {


            if (Membership.ValidateUser(username, password))
            {

                if (Roles.IsUserInRole("Saleman"))
                    Response.Redirect("~/Saleman.aspx");

                else if (Roles.IsUserInRole("Accountant"))
                    Response.Redirect("~/Accountant.aspx");

                else if (Roles.IsUserInRole("HR"))
                    Response.Redirect("~/HR.aspx");


                //Always receive Attempt to login failed message !!
            }
        }
    }

When you created each user did you approve their account? Make sure each user is in the 'approved' status, otherwise they won't validate.

Problem solved, incorrect syntax, i should use it like that: Roles.IsUserInRole(string username, string rolename){}

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