Currently Being ModeratedJan 17, 2013 11:11 AM (in response to tamedspirit)
Assuming "Total Miles" is the name of a column,
=SUMIF($Category,Mileage Categories :: A1,Total Miles)*0.24
Numbers uses column references two different ways. If the formula requires a range it treats it that way (the range = the entire column). When it requires a single cell, it uses it that way. By multiplying the column reference by 0.24, you are treating it as a single value, not a range, so it becomes a single value (or, more precisely in the context of the formula, it is a range that consists of a single cell). The formula needs a range that is the same size as the one in the first parameter. Thus the error.