请问下面的程序为什么出现错误(0分)

procedure TForm1.Button1Click(Sender: TObject);
var s:Tstringlist;
ms:Tmemorystream;
begin
ms:=Tmemorystream.Create;
s:=Tstringlist.Create;
s.Add('LoginName=tmnet@zzu.edu.cn&Password=hl3887403@');
try
idhttp1.post('http://mail.zzu.edu.cn/cgi-bin/login',s,ms);
ms.SaveToFile('c:/stream.txt');
finally
ms.Free;
end;
end;

end.

ms.SaveToFile('c:/stream.txt')就是这里出现错误

TTTTT

procedure TForm1.Button1Click(Sender: TObject);
var
s:Tstrings;
ms:TstringStream;
begin
//注意idhttp1设置handleRedirect 为true
ms:=TstringStream.Create;
s:=Tstringlist.Create;
s.text :='LoginName=tmnet@zzu.edu.cn&Password=hl3887403';
try
idhttp1.post('http://mail.zzu.edu.cn/cgi-bin/login',s,ms);
except
end;
ms.saveToFile('File');
ms.Free;
end;

end.

procedure TForm1.Button1Click(Sender: TObject);
var s:Tstringlist;
ms:Tmemorystream;
begin
ms:=Tmemorystream.Create;
s:=Tstringlist.Create;
s.Add('LoginName=tmnet@zzu.edu.cn&Password=hl3887403@');
try
idhttp1.post('http://mail.zzu.edu.cn/cgi-bin/login',s,ms);
[red]ms.Position := 0;[/red]
ms.SaveToFile('c:/stream.txt');
finally
ms.Free;
end;
end;

错误与服务有关系