MDX calculations using multiple time dimension elements

Question

We have an OLAP cube with the following dimensions: Ship_Date, Product, Customer. The measures are Units, Cost, List Price, Sell Price.

We want to set up calculations of Cost/Unit, List Price/Unit and Sell Price, like the below:

[Measure].[Cost]/[Measure].[Units]

This works with one time elements (All Ship Dates, 2016, Jan 2016, etc.) but when multiple elements are selected, like 2016 & 2015 or Jan 2016 & Feb 2016, the calculation does not resolve correctly which we think is because it is summing the ratios instead of calculating against the sums.

I tried the below calculations to similar results:

SUM([Ship_Date].CurrentMember.Level.Members,[Measure].[Cost]) / 
SUM([Ship_Date].CurrentMember.Level.Members,[Measure].[Units])

SUM(Descendants([Ship_Date].CurrentMember, [Month]), [Measure].[Cost]) / 
SUM(Descendants([Ship_Date].CurrentMember, [Month]), [Measure].[Units])

Aggregate(Descendants([Ship_Date].CurrentMember, [Date]), [Measure].[Cost]) / 
Aggregate(Descendants([Ship_Date].CurrentMember, [Date]), [Measure].[Units])

I'm very new to MDX - can someone please point me in the right direction?

Answer 1

Maybe try playing with the calculation's solve_order: https://msdn.microsoft.com/en-us/library/ms145539.aspx

DIVIDE(
   [Measure].[Cost]
  ,[Measure].[Units]
)
, SOLVE_ORDER = 1  //<<also maybe try -1 or -6500