Hi Tobiasz22:
The only clue I see, is the possibly it is language related? I searched my English version of Excel for #ARG! and did not fine any help. I also searched the internet an did not find any clues. There is a strong possibility that some of the formula (as written) do not recognize some cells. I notice on your screen clip, that where my version is "TRUE FALSE" your screen shows it in your language. There are also other cells on the spreadsheet, that also may be language specific.
As you might guess I have spent many hours, on this and seen many errors, and problems, but nothing of that nature. Maybe someone else with different language versions of Excel can help. If you or anyone find a problem with the code or a more universal solution, I would greatly appreciate it.
PLEASE let us all know if you find a cause and a solution.
Regards
canuk