Getting Negative Numbers

Getting Negative Numbers

I created a form called business plan and basically each field has a calculation in it. For example i have fields quarter 1, 2, 3 and 4. And it breaks down how much money a person has brought it for each quarter. but if i enter in data say for quarter 1 and 2, quarter 3 and 4 will have a negative 3 instead of 0. Can someone please look at my script and let me know how i can fix it. I have allowed edit access to support. Thank You