Rankx - Summarized level

Hi All,

I've got order detail data that i would like to summarize on order level and the rank each order by size.

My data looks like this:

CompanyCode - CustomerCode - OrderNum - OrderLine - Product - Qty - Price

What i've done is create a measure called "Total Sales" = SUMX(OLine;OLine[OrderQty] * OLine[UnitPrice])

which gives me a sum for each line.

but some orders have many lines, and when i try to use the RankX function, it only ranks the lines by size. So i was wondering if there is a way of getting the rankx to look at each OrderNum and add up all OrderLines and then give me the ranks.

Thanks.