QR code won't scan at post office

[luxmann-83]

Had 2 different codes now and both not working 

[tommystrezures]

Was there a  particular reason? your screen has to be quite bright if using your phone. for teh scanner to pick it up, If a print out don't make it too big.

[luxmann-83]

Hi just when they scanned it it beeped and she just said it not working QR code so got another one from ebay and still not worked