Can't register FP5

I always get “Fill day/month/year” to continue. The NEXT button is disabled. What can I do?

Both on mobile phone (FP5 / Firefox Klar) and my PC (Firefox)

Have you also tried with a date that is NOT in the future?


While I dislike the form of your answer, it was semantically helpful: it was indeed the problem that I misread “6” for an “8” on the invoice.