Build 4.0.0.92 of xlsgen fixes a problem related to pivot tables.
A new method is introduced in order to make it possible to aggregate data in rows instead of columns (which was and still is by default). This is a method and not a simple boolean property because the client application can choose the position of this aggregate data in rows, or in columns, as the display follows the order of pivot fields in each of the 4 quadrants (Rows, Columns, Data, Page).
Here is how to aggregate data in rows :
pivottable.Rows.AddDataFields();