[Pisces]

What does "does not work" mean? Do you not notice a difference in game(play) compared to before the enabling of the mods. Or does the game crash at some point?

This is an important distinction to isolate the probable cause.

[EDIT]Please write down exactly how this mod is named and placed (with it's immediate subfolders )in your MODS folder.

It should NOT be like:

SilentHunter4\MODS\FJB_Navigation_Maps\FJB Two Tone Navigation Map\Data\ (etc.)
SilentHunter4\MODS\FJB_Navigation_Maps\FJB Color Navigation Map\Data\ (etc.)
SilentHunter4\MODS\FJB_Navigation_Maps\FJB Brown Navigation Map\Data\ (etc.)

If you have the above, you will also find a file in this folderpath: SilentHunter4\FJB_Navigation_Maps\FJB Navigation Maps.pdf
This wil do no harm though.

You should have the 3 map-submods as seperate in the MODS folder for enabling to work correctly: (and nothing in between)

MODS\FJB Two Tone Navigation Map\Data\ (etc.)
MODS\FJB Color Navigation Map\Data\ (etc.)
MODS\FJB Brown Navigation Map\Data\ (etc.)

The pdf would then be located in the MODS folder, which would not be copied to the game folder. So you either put it in the SilentHunter4\docs folder manualy. Or add a docs folder to each submod, and place a copy of the pfd in each, or whichever you intend to use.