Well st_swithin the ATP is actual called the Apolyton Tile File and contains a modified gtset565.til file, actual I never saw an include in this file.
For me it looks rather like bartek downloaded the latest version of the city expansion set and clicked in ModSwapper on "Apolyton Pack + City Expansion v2.2!" instead of "City Expansion Mod v2.2" without installing Apolyton Pack first.
Well bartek if you want to play City Expansion Set with the Apolyton Pack you first need the files of Apolyton Pack at the right place otherwise the game will tell you that some files are missing.
-Martin