SUMIF Formula For Values In Different Rows

I thought that SUMIF FUNCTION should work for what I am trying to achive but it does not look like.
Here is the example: 1,2,3 etc. are rows and A, B,C - columns
A B
1 Gain (Loss) on Balance sheet reval, 91105(2,035,611)
2 Expense
3
4 NET Gain (Loss) on LTD 945,600
5 including Hedge on $ million Revenue

I need to write the formula in cell e.g. A8 that would look at my either "Expense" or "Revenue" and sum it if it is revenue or sumit if it is expense. I have the whole spreadsheet of rows and the label "revenue" or "expense" repeats almost always after 2 rows.