Sorry, I didn't really finish my explanation.
With 2 summarized fields, each grid on the report would have 2 values in it. The sum and avg of each detail value (it is the same value), and for each row total you would have both the sum and average for the row, the same for each column total, and likewise for the grand totals.
I wanted to display the averages for the column totals and sums for the row totals, so I suppressed the values I didn't want to see.
If there is a way to control the display other than that, I would like to know about it.