Flight not available - what does this mean?

Hi, I'm trying to book a return flight from Lappeenranta, Finland to Dusseldorf, Germany (going out on November 18th, 2012, coming back on November 21st, 2012, dates flexible) but it doesn't show any flights in that week. I tried going back and checking the previous dates. The latest date that the flight is available is November 4th. Well, of course it shows several options why the flight is not available but I would really like to know which one is more likely. I certainly don't believe that the flights are full (there are no flights at all after November 14th). I would like to think that actually "The travel dates requested are for our next schedule period and the fares/seats are yet not loaded for these dates." But could it be possible that this route is simply cancelled after November 4th?

If I remember correctly, Ryanair changed this route to seasonal, so it should return next summer. This winter however the route will not be operated.