Some time ago I noticed that there are some confusing messages on French websites which say things like "Votre adresse e-mail a changé" or "Vous n'avez pas encore payé les frais" - which cause me to think "what's this about? I haven't changed anything" or "I'm sure I sent them a cheque" or whatever. Eventually I realized that they're not telling you "your address has changed" or "you haven't paid" - they're saying if your address has changed or if you haven't paid, then you need to do the following.
In other words, it's just a French habit of leaving out the word "si".
Even though I'm now aware of it, I still got caught out recently. I was entering payment details for a bank, and the bank's system had automatically entered an address based on a reference number. Then when I got to the bottom of the page, there was a message saying "L'adresse n'est pas correcte." Since the address had been supplied by the bank itself, I couldn't do anything, but I wrote to them pointing out what seemed to be a bug in their system.
They wrote back politely explaining that it wasn't a bug; it was there so that if the address seemed to be wrong, I could click on the message to get help. "Dumb foreigner", I could hear them thinking.