Calculation based on Distinct Order ID

[rqh]

Hi everyone 🙂

I want to create a measure to calculate total shipping costs, based on unique Order ID. I am using a star schema, so Order ID is not unique.
The main issue is Freight (shipping costs) is also not unique, so whenever I use SUM(), it sums everything, which is not what I want.
My attempt:
Total Freight := CALCULATE(SUM('Orders'[Freight], DISTINCT('Orders'[Order ID]) --which ended up being the same as SUM('Orders'[Freight])
I got $107K but should be getting $32K. Please help ^^'
I'll attach some screenshots.

[Fowmy · Accepted solution]

@rqh 
Try  this measure:

Total Freight = 

SUMX (
    DISTINCT('Orders'[Order ID]),
    CALCULATE ( MAX( 'Orders'[Freight] ) )
)

[rqh]

Great solution, you're a godsend.