idhttp post 问题

procedure TForm1.Button1Click(Sender: TObject);
var
  filestream:TIdMultiPartFormDataStream;
begin
  zipname:=extractfiledir(application.exename)+'\upload.zip';
  filestream:=TIdMultiPartFormDataStream.Create;
  filestream.addfile('file1',zipname,'');
  idhttp1.Disconnect;
  idhttp1.post('http://192.168.1.2:8086/sb/gssbServlet',filestream);
  idhttp1.Connected;
end;文件路径及文件名没问题，链接没问题，为什么执行到idhttp1.connected;的时候老是报错
错误信息为 500 internal server error 请问有什么办法搞定吗？