Limiting/Tracing every other column Sum

[GerryK]

Good Day,
In testing my spreadsheet I have found an error that I
believe I have resolved but remains a huge mystery to me.
I would appreciate any expert opinions please as this has
a fairly serious repercussion potential in my workbook.

In D2 I have:
SUMPRODUCT((MOD(COLUMN($I$2:INDEX(2:2,72))-CELL("Col",$I$2)
+0,2)=0)*($I$2:INDEX(2:2,72)))

I am trying to add up I2,K2,M2.BS2 (for a total of 32 sums
and must stop at this point).


In E2 I have:
SUMPRODUCT((MOD(COLUMN($H$2:INDEX(2:2,72))-CELL("Col",$H$2)
+0,2)=0)*($H$2:INDEX(2:2,72)))

I am trying to add up H2,J2,L2.BR2 (for a total of 32 sums
and must stop at this point).

A value in BT2 was showing up in the addition at E2 so I
traced precedents and found that the group stopped at BS2
and should not have included BT2 (visually). By changing
the 72 to 70 I got rid of the BT value but tracing
precedents did not show a different grouping.

Have I indeed grouped my cells properly now? Is there an
anomaly with 'trace precedents'?

Thanks to this group for bringing me to this point so far!