I did a couple of tests to try to see what is wrong. First I downloaded one of my own F4F skins from AH Skins and it worked fine.
Then I tried renaming the F4F41 directory to F4F43 and that skin disappeared from the game. Changing the name back to F4F41 brought the skin back. This effect wasn't universal however, when I changed the F4F42 directory to F4F44 it remained in the game.
So I suggest you try Oct's suggestion and rename your F4F42 directory F4F41.