I got parking fine in Düsseldorf, but when I try to pay it, an error pops up

Hello guys, so this Sunday I was visiting my friend in Düsseldorf and parked in front of her house and got a parking ticket. To be honest, I kind of asked for it with my parking😂

But now when I try to pay it, the following error (in the pic) pops up. What should I do?

Do you think it could be that my car has a Belgium number?

https://i.redd.it/2v5m8id962vc1.jpeg

Posted by 0007sfr