The default is Excel mode for subtotals
This uses an Excel formula to calculate the totals. Any calculated members are totaled after the query is run and may not return the number you want. For example, such as summing the average or percent numbers.
Cube mode does the sub-totaling as part of the query. This means that (if the cube calculations work) any Average or Percent calculations stay the same.
Use the Grid ribbon to switch between the two modes.
