I've run into this a few times recently, so here's a quick tip related to using Excel with Oracle OLAP (via the Simba MDX Provider for Oracle OLAP, of course).
Here's a situation that's been reported as a bug, but you really just need to know the right Excel Pivot Table option to choose. Consider a cube that has measures that do not aggregate but is dimensioned by a dimension with a hierarchy. In this case, there is a cube with a Store dimension with levels Store > Store Type > All Stores. The stores are located in different countries and sell in local currencies. There is a Local Currency measure, with sales reported in whatever the local currencies might be (Euros, Dollars, Yen, etc.) and a Dollar Sales measure with the U.S. Dollar conversation. As a common currency, Dollars can be aggregated. Local currencies can't be aggregated.
Here's a sample report in Excel.
Note that Dollar Sales is reported for Direct and Indirect but Local Sales is not. That's correct because Local Sales doesn't aggregate.
But what if I happen to select only Local Sales (which is null at the aggregate members Direct and Indirect). By default, Excel will display the report as shown below.
This isn't very useful because I can't drill down on the Direct member to get at the stores. The solution is simple, but a lot of people seem to miss it. Just choose the Show items with no data in rows PivotTable option.
Now you will be able to see the Direct and Indirect members, allowing you to drill to stores.
Now, after the drill.