I booked a flight on the KLM site several months in advance and got the line: "U kunt niet online inchecken voor deze vlucht." (You can't check in online for this flight.) The flight is on a national holiday and I was pretty much sure at the time that the reason for not being able to check in online was that holiday. This is a standard flight, booked on the KLM site directly, by someone who is a Dutch citizen and who has checked in online with KLM several times in the last few years.

Is there a way out and still be able to check in more than three hours before the flight?