subtraction of column Formula

I make a formula (E1-F1) on column G.

E1 and F1 are money.

When I have the G column as Free text the formula works, but when you press calculate totals it does not work (Probably it thinks that this is text and not numbers, so can not sum).

when the column G is Money or number the formula does not work but if you put a number by hand it calculates totals