@R0bperry904 this questions over 2 years old, but I was having a similar problem on an excel sheet that had been fine previously and found that there was a hidden sum in the columns I was implementing a formula on if that makes sense. Found it in the formula bar. From the sheet itself it was showing 0, I had to click on it and then I could see that the cell had a formula already imbedded. Removed it and then my formula was working again.