XLM Payload als Post

[strom]

Hallo, bekomme es einfach nicht hin! Fehlercode E/A 105 ??

Delphi-Quellcode:

procedure TForm1.Button2Click(Sender: TObject);
var
  HTTP: TIdHTTP;
  RequestBody: TStream;
  ResponseBody: string;
begin
  HTTP := TIdHTTP.Create;
  try
    try
      RequestBody := TStringStream.Create('{123456789}',
        TEncoding.UTF8);
      try
        HTTP.Request.Accept := 'input.xml HTTP/1.0';
        HTTP.Request.ContentType := 'application/x-www-form-urlencoded';
        ResponseBody := HTTP.Post('http://login.fireboard.net/api?authkey={123456789}&call=operation_data',
          RequestBody);
        WriteLn(ResponseBody);
        WriteLn(HTTP.ResponseText);
      finally
        RequestBody.Free;
      end;
    except
      on E: EIdHTTPProtocolException do
      begin
        WriteLn(E.Message);
        WriteLn(E.ErrorMessage);
      end;
      on E: Exception do
      begin
        WriteLn(E.Message);
      end;
    end;
  finally
    HTTP.Free;
  end;
  ReadLn;
  ReportMemoryLeaksOnShutdown := True;
end;