Sumif

I need to change cells to reflect new costs. Then have these costs roll into new totals.

I attached a worksheet to demonstrate how it works. The numbers in gray should be adjustable. The numbers in tan are summing up incorrectly with my "SUMIF" formula.

Any thoughts to make this work? I should be able to put Current Costs back into New Cost box and get original totals. But I don't.

Thank you much for any help you can give.

Roger!