Unable to retreive public spreadsheet

[PYDeret]

As the exemple says, you're not required to authentify to retreive public spread sheets, just need the public id.

$serviceRequest = new DefaultServiceRequest("");
ServiceRequestFactory::setInstance($serviceRequest);

$spreadsheetService = new Google\Spreadsheet\SpreadsheetService();
$worksheetFeed = $spreadsheetService->getPublicSpreadsheet("spreadsheet-id");

But I'm getting the Access token is invalid error.

Maybe I've done something wrong.