German Occupation Stamp: Scott Russia N9?

When I look in my Scott 2009 Volume 5, Russia, I find the following stamp listed as N9. However, in the catalog software I am using it comes up as N21. Also, when I looked at HipStamp I find that "N9" comes up as my stamp and a Germania overprinted stamp.
https://www.hipstamp.com/search?key...&parent_id=0

Between 2009 and now did Scott change the catalog numbers for the Ostland overprints stamps? Or is there something else that I am missing.

Thanks for the help.

The Scott 2014 Volume 5 lists it as N9.

Robert

Cancellation appears to be (Ple)skau, or Pskov, Russia. This is 12 km. from the Estonian border. This area was also part of the German occupiers' "Ostland".

@Trainwreck: Thanks for the verification.

@bookbndrbob: Thanks for the cancellation info.

And now I have been informed that in the Scott 2018 catalog the Lithuania (under WW1 German occupation) 1N1 to 1N12 stamps to Russia N1 to N2, with the Finnish and WW2 German occupation stamps shifted accordingly. Hence N9 is now N21. Looks like it is time to start thinking about getting an updated set of catalogs.