Report of expense account under income account

[Diego]

I am trying to get the "Expense Piechart" report for all expenses in the 
following structure:

Events (income)
      Event1  (income)
            income  (income)
            expenses  (expense)
      Event2 (income)
            income (income)
            expenses (expense)

When I try to run the report it says:

"No data
The selected accounts contain no data/transactions (or only zeroes) for 
the selected time period "

If I change Events to be an "Expense" account instead of "Income", it 
does generate the report correctly. Is this the expected behavior?

I still need to keep Events, Event1, and Event2 as income accounts (for 
other reports, and the "signs" of numbers in different contexts).

I'm running Gnucash 2.6.5 under FC20.

Thank you,
Diego