need to use a shared variable and formulas...maybe running totals, but my preference is shared variables.
3 formulas
in group header reset:
shared numbervar aVar:=0;
in group footer display
Shared numbervar aVar
in Details increment:
shared numbervar aVar;
if not suppressed then //suppressed is your criteria
aVar := aVar + {table.field}; //the amount to increment.
HTH