RangeSum Week Sales

[Anonymous]

Any way that Range Sum can be used to sum up the previous Calendar weeks sales?  I have an expression, but it does not provide the desired data.

Expression I have:

RangeSum(Distinct{$<Timestamp([completed_date])={">=num(today())-7<=num(today())"}>}(order_total), (order_id))

Maybe using week, weekstart, or weekend functions, but not sure.  Any help?  Thanks in advance.