I'm having problems with an If statement that will not execute. The same function works fine when I copy-paste it to an other cell, but it simply does not work for the cell that I want. Anyone who's had the same problem?

Here is my function:
=HVIS(Inngangsdata!C5=0;"";Inngangsdata!C5)

('Hvis' is 'if' in norwegian, 'Inngangsdata' is just the name of the page from which cell C5 is taken).