Applying SortKey on a Crosstab Section

[RL_Boston]

Hi All -

Basically, I have two queries, that Join on a Data Item (Products). In the Joined Query I have another Data Item that has a Case Statement which groups the results into a "Product Category". I then created a Section based on this Product Category but would like them to be sorted in a specific order. Therefore I created a SortKey  and applied it to the Section, but I get an aggregate error.

Does anyone know if a SortKey on a Section is allowed in Cognos? 


Thanks in advance!