看不见

我用的是idsmtp及idmessage组件,写了如下程序,正常编译后,出现了上述对话框.源程序如下:
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, IdMessage, IdBaseComponent, IdComponent, IdTCPConnection,
  IdTCPClient, IdMessageClient, IdSMTP, StdCtrls;

type
  TForm1 = class(TForm)
    edtfrom: TEdit;
    edtusername: TEdit;
    edtpsw: TEdit;
    edtto: TEdit;
    edtsubject: TEdit;
    edthost: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Label5: TLabel;
    Label6: TLabel;
    Label7: TLabel;
    edtattach: TEdit;
    memcoment: TMemo;
    Label8: TLabel;
    Button1: TButton;
    Button2: TButton;
    IdSMTP1: TIdSMTP;
    IdMessage1: TIdMessage;
    OpenDialog1: TOpenDialog;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
if opendialog1.execute then
self.edtattach.text:=opendialog1.FileName
else
begin
self.edtattach.text:='';
showmessage('没有附件');
end;
 end;
procedure TForm1.Button2Click(Sender: TObject);
begin
self.IdMessage1.Clear;
self.IdMessage1.From.text:=edtfrom.text;
self.IdMessage1.Recipients.EMailAddresses:=edtto.text;
self.idMessage1.body.assign(memcoment.lines);
self.idMessage1.subject:=edtsubject.text;
if edtattach.text<>'' then
tidattachment.create(idmessage1.messageparts,edtattach.text);
self.idSMTP1.authenticationtype:=atlogin;
self.idSMTP1.username:=edtusername.text;
self.idSMTP1.password:=edtpsw.text;
self.idSMTP1.host:=edthost.text;
try
self.idsmtp1.connect();
try
self.idsmtp1.send(idmessage1);
showmessage('e-mail已经到达');
finally
self.idsmtp1.disconnect;
end;
except
on e:exception do
begin
showmessage('e-mail发送失败;'+E.Message);
end;
end;

end;

end.