Taken out of context, this is damn difficult to explain. The expression refers to at most 31 previous cells in a chart/table so Sunny is probably right. Also, in each separate month, it will not pass the current day number, so its a "DayToDate" accumulation, if you can call it that way.
Can you post a screenshot with the chart dimensions?
Entering an expression like this in the expression editor and adding whitespace makes it a lot more readable. Like so:
if (DAY < Day(Today()), // Only for daynumbers smaller than today's day number
rangesum(
above(
sum({$<Year={$(=max(Year))}, // max selected year, max month in that year
StrikeReturnPartial={Strike},
Month={"<=$(=Max({<Year={$(=Max(Year))}>}Month))>$(=Max({<Year={$(=Max(Year))}>}Month)-1)"}
>}
Amount),
0, 31) // Go back max 31 days
) * -1, // Invert
'' // Display nothing for days >= today's day number
)
AFAIK it may do weird things in January.
Peeter
