.....Date...........Prod A.......Prod B........... Prod A diff.............................Prod B diff
03/31/2015........764...........785
04/10/2015........502...........655...........9 (04/10 - 03/31)......................09 (04/10 - 03/31)
04/15/2015........761...........................4 (04/15 - 04/10)
04/21/2015........628...........................5 (04/21 - 04/15)
04/23/2015........247...........................3 (04/23 - 04/21)
04/24/2015........074...........227...........2 (04/24 - 04/23)......................11(04/24 - 04/10)
04/29/2015........530...........322...........4 (04/29 - 04/24)......................04 (04/29 - 04/24)

I expect a formula for Prod B diff column because if the above cell in prod b is blank, it should take the next above non blank cell in Prod b and get the networkdays() for the corrresponding cells.

Thanks