Hi,
If while running query someone use free characteristicts that are not in your aggregate the aggregate will not be used.
Haven't you added anything to filter of query ? May be some time characteristic ??? . It's important too.
In your aggregate you have to include all characteristics that are used while displaying data in the query (filtering and aggregating).
You don't need to add all free characteristics to the aggregate. If you added to your query some characteristics as free characteristics the qggregate should work unless you want to drill down the data using those free characteristics.
Regards Leszek