Interactive Sort Has Probs

Hi All,



I've designed a simple sales report , first grouped by Transport type and then by item.

Example

Category Item Sales



DHL A 2000

DHL C 1500

DHL E -1700



AmEx A 200

Amex E 20



-------------------------------

when click on sales under group DHL it shouild sort -say descending-

so result should be

DHL A 2000

DHL C 1500

DHL E -1700



instead I get results



DHL A 2000

DHL E -1700

DHL C 1500



this is just an example but this is the sort of results I get when I try to use interactive sorting.

Any Ideas?



thanks



Sonny