Sometimes when I build a nested formula, the results don't show in the
cell. The only thing that shows is representative how the cell is formated,
ie: number format with 2 decimal points displays "0.00"

When I click on the cell with the formula, it appears in the input box. If
I click the equal sign, the drop-down menu shows the correct results, even if
I change the data it uses to determine the answer.

=AVERAGE(IF(A1:A12="Hours",C1:C12))

This is the formula. I intend to extend the range from 12 to about 90 when
it works.

Basically, what I want is to check for the word "Hours" from column A and
if it finds it, average the data from the corresponcing column C.

Since "Hours" is every 4th line, I was looking for a "step" function
simular to the one used in BASIC.

Any ideas?