Date range calculations using Above.

[#1]

I have the following in a Qlik Sense pivot table:

Rows:

  InvoiceMonth & '-'& Invoice Total

    InvoiceMonth > '2016-02'

    ascending order: (... 2016-12/ $80M , 2017-01 / $55M, 2017-02 /65$M)

Column:

  PaymentSeq (Column: 0,1,2,3,4,5,...,n)

Measures:

  [Paid]:

  SUM( TOTAL <InvoiceMonth,PayerName,PaymentSeq>Paid) //offset 1, 6-mos back

  [Avg Pymts Prev 6-Mts Avg]:

  rangeavg(above(SUM( TOTAL <InvoiceMonth,PayerName,PaymentSeq>Paid),1,6))  //offset 1, 6-mos back

  [% Paid Last 6 months]:

  rangesum(above(SUM( TOTAL <InvoiceMonth,PayerName,PaymentSeq>Paid),1,6)) / rangesum(above(SUM( TOTAL <InvoiceMonth,PayerName>Invoiced),1,6))

The top few rows will give wrong 6-mt averages. I have data for 2015 and 2016, but  "ABOVE with TOTAL" won't see beyond what is visible in the 12 -mt table. I need it to calculate the average 6-mt on top rows.

I don't know a way to fix this using the "ABOVE" function. I've tried to adapt to different ways using AGGR but could not get it to work.

Any solution would be very appreciated.