Pivot table - Custom calculation question
 

I am trying to create a pivot table for keeping track of the scrap rate in a
factory. I have a pivot table with two data fields, one for input parts and
one for defect parts. I want to show the defect parts as a percentage of the
input parts. Whenever I use the "% of" function in "Show data as" I get #N/A
in the defect parts column.

The method I am using is that I click a cell in the defect parts column, go
to Show data as in the Field Settings, Chose "% of" and then use input parts
as the base field.

Both input parts and defect parts are data fields in my pivot table. There
is no missing data. What am I doing wrong??