Trouble Calculating Subtotals using All functions

I am attempting to calculate the % of the material cost of a part based on the overall material cost of all parts in a given location. I assumed it would be straightforward with <single part cost>/<overall cost> but I am having trouble getting the denominator using Calculate and All functions, can anyone tell me what I am doing wrong?

I have one table with sales orders like so:

I have several other dimension tables connected to this, but most importantly I have a Part table with associated costs that is linked in a Many to 1 relationship to the Sales Order table:

First I create a measure for the cost unit cost: UnitCost = sumx('Part Table','Part Table'[Unit Cost]).

I also create a Qty measure just for convencience: OrderQty = sumx('Sales Orders','Sales Orders'[Qty])

Then I calculate the material cost for the order by multiplying Qty * Cost but I need to do some extra DAX in order to ensure that it multiplies and then sums (it was giving me incorrect totals because it was summing and then multiplying when I did [UnitCost] * [OrderQty]).

The ExtCost measure: 

ExtCost = sumx(Values('Sales Orders'[PartId]),CALCULATE([UnitCost] * [OrderQty)).


So now I would like to calculate % cost for a given sales order at a location: %ofCost = Divide([ExtCost],[TotalLocationCost]) but I am failing to get the correct amount for TotalLocationCost. I assume it is some combination of Calculate and All but I tried 

[TotalLocationCost] = calculate([ExtCost],ALLSELECTED('Sales Orders'[Warehouse])) and it is just returning the same amount as Ext Cost and thus my % is always 100%.

 

I would like Warehouse Ext Cost to be $41,200 for each row.

 

 

I still have a bit of trouble wrapping my head around the ALL functions, can anyone point me in the right direction?

 

Thanks.