Sorting and grouping

[KHogwood-Thompson]

I have a Balance Sheet report that is grouped by the type of item, i.e. Fixed
Asset, Current Asset and Current Liability. This works fine and using
grouping I can get totals of each group type shown above.

The problem is when I want to show a total for Net Assets, i..e Current
Assets minus the Current Liabilites. I have a group field in the underlying
query called "Balance Sheet Type", I have Net Assets against all Current
Asset and Current Liability items for this field, I want to have a total for
Net Assets in the detail section of the report. I have tried adding a group
to the report but that shows the total against each item rather than at the
end of the Current Liability section.