Summing values in Pivot Table Grand Total Column

[Chalklands]

Hello,
I have a pivot table showing unit sales by month in columns, product numbers in rows with a Grand Total of the columns. For example:

Jan Feb Mar Grand Total
Product 1 25 25 0 50
Product 2 0 -10 0 -10
Product 3 10 -15 -5 -10

I want to sum all of the values that are negative (credit returns) from the grand total column in another part of the spreadsheet.

So in the example I want to return the value -20

However the Grand Total column position is not fixed as new months will be added as the year progresses so the Grand Total column will move to the right as the year progresses.
I was thinking about using HLookup. am I on the right track?

Pete

 

[sheetspread]

Instead of a formula why not set another pivot table with just the row and value, then filter out positive totals?

 

[LloydFinancials]

=SUMIF(INDIRECT(SUBSTITUTE(ADDRESS(1,MATCH("Grand Total",A1:ZZ1,0),4),"1","")&":"&SUBSTITUTE(ADDRESS(1,MATCH("Grand Total",A1:ZZ1,0),4),"1","")),"<0")

A1:ZZ1 is some all inclusive range for row 1 for instance that has the words "Grand Total".