I have a series of cells filld with formulas, but the value of the cells is
null.

I then in some other cells used if function, which will evaluate the above
cells, and if the value of the above is null then output something like "-",
otherwise some real numbers. However, when the reference cell values are
blank, excel continuously gives me error messages. I wonder if it's the
formulas underlying those cells are screwing everything up. And if yes, is
there a fix to this?

thanks,