Hello

I have 2 columns with data. I want to create a Pivot table which shows me
the sum of column A and column B by month, and I want a 3rd column showing
the difference between the col. A&B. I created a sum of col A, sum of col B,
then added col B again, click Field Setting and choose show data as:
Difference From, in base field, choose col B, and base item, chose
(previous). But, it's not working and giving me #n/a. i tried to flip it,
but nothing seems to be working.

Please help!
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Thanks