Sequence When Using Constants and Summation in DSO Transformations

I am experiencing what appear to me to be inconsistent results when using rule type "Constant" with aggregation of "Summation" in two different DSO Transformations. In each case, I am attempting to summarize data from a more detailed DSO into a less-detailed DSO, while counting the number of records in the source DSO.

Case 1: Count the number of Sales Document Lines for a Given Shipping Point

Source DSO Key is 0DOC_NUMBER + 0S_ORD_ITEM

Data Fields: 0SHIP_POINT

Target DSO Key is 0DOC_NUMBER + 0SHIP_POINT

Key figure K_QUALSOL - Rule details:Rule Type = Constant, Constant Value = 1, Aggregation = Summation

This one works; it correctly counts the number of sales doc lines for each shipping point. I assume that it works because it assigns a constant value of 1 to each SOURCE record prior to doing the summation. Correct?

Case 2: Count the number of Deliveries for a Given Sales Document / Shipping Point Combination

Source DSO Key is 0DELIV_NUMB + 0REFER_DOC + 0SHIP_POINT

Target DSO Key is 0DOC_NUMBER + 0SHIP_POINT

Note that 0REFER_DOC in the source DSO is mapped to 0DOC_NUMBER of the target DSO

Key figure K_NUMDEL - Rule details:Rule Type = Constant, Constant Value = 1, Aggregation = Summation

This one DOES NOT WORK! I assumed that it would assign a constant value of 1 to each SOURCE record prior to doing the summation, but instead it appears to do the summation, and then assign a constant value of 1 to each TARGET record.

Why the difference in behavior?