#17 Can't change size

[Tom Chubb]

It doesn't matter which code I use, but I always get the same sized QR code.
I've tried the following;
QRcode::png('PHP QR Code :), $pngAbsoluteFilePath, 'M');
QRcode::png('PHP QR Code :), $pngAbsoluteFilePath, QR_ECLEVEL_H, 4, 4);
QRcode::png('PHP QR Code :)', $pngAbsoluteFilePath, 'L', 4, 2);

All are the same size. Why is this?