What puzzles me is the fact that the code is well working with other fields, but not in this case...

Thank you, but this does not help. What I get is a white field with a white text and an icon. 

if 'investiertes Kapital abzüglich Ausschüttungen und Steuererstattungen' < 'aktueller Kurs' * Anzahl then
styled("Gewinn", "green", "white", "arrow-n")
else
if 'investiertes Kapital abzüglich Ausschüttungen und Steuererstattungen' >= 'aktueller Kurs' * Anzahl then
styled(text("Verlust"), "red", "white", "arrow-s")
end
end

What could be the problem?

Thank you

Or simplified:

if 'investiertes Kapital abzüglich Ausschüttungen und Steuererstattungen' < 'aktueller Kurs' * Anzahl then
styled(text("Gewinn"), "green", "", "arrow-n")
else
styled(text("Verlust"), "red", "red", "arrow-s")
end

I wonder why in this constellation I cannot change the background color of the cell. It is just not shown.

Thank you, Nick. The problem was that the setting of the field itself overrule. as Steven indicated. Although I just centered the cell, it seems that even this results in overruling color settings. Thank you, problem solved.