When are aggregates not used???

Hey All,

I have a question concerning aggregates and when they get used. I have a user running a query and specifiying values in the selection criteria for the following:

- Sold-to Party

- Distribution Channel

- Site

- Condition Type

- Calendar Week

All 5 of these Characteristics are part of the new aggregate I build. I guess I don't understand why the aggregate is not being hit, if they're reporting on the exact same Characteristics that are part of my aggregate.

Can anyone explain????

Much appreciated.

John