you can't place the 3rd formula in the page header...
it will always display zero because you have not 'read' / calculated the 3rd formula, because the 2nd formula has not been accessed...not in the page header.
If you want to display the total from the prior page, then display the 3rd formula in pageHeader1, and create a second page header section BELOW the one that displays and place the first formula there.
HTH