Thx for your reply Rocky !
In expression tab you can indeed perform the calculation you suggested.
However in the sample report the expressions are placed in the pivot table rows
and calculations (sales/kg) have already been done there.
The growth calculation between 2009 and 2010 is a calculation between dimension
members. I don't see how this can be done in a QV pivot table .
If you any more suggestions, please let me know .