Need help to create measure for unallocated sales allocation to other categories

[Explico]

Hey. I do have sales data set where part of the sales is "unallocated" i.e. sales department is missing. I need help creating measure, which would allocate  those "unallocated" sales to other available departments proportionally (based on their sales). This is what I do have and what I'm trying to achieve:

Need to play with filters, but that part is still quite confusing for me. Thanks in advance!

[Jos_Woolley · Accepted solution]

Hi,
Assuming you already have a measure named TotalSales, defined as:

Total Sales =
SUM( 'Table'[Sales] )

create the following additional measure:

MyMeasure =
VAR Department =
    MIN( 'Table'[Department] )
VAR SalesUnallocated =
    CALCULATE( [Total Sales], 'Table'[Department] = "Unallocated" )
VAR SalesExcUnallocated =
    CALCULATE( [Total Sales], ALL( 'Table'[Department] ) ) - SalesUnallocated
VAR MyWeight = [Total Sales] / SalesExcUnallocated
VAR AdjustedSales = MyWeight * SalesUnallocated + [Total Sales]
RETURN
    IF( Department = "Unallocated", 0, AdjustedSales )

Regards

[Explico]

Hi. Thanks @Jos_Woolley ! 

Almost works, but strange behavior with Matrix Total. Any ideas?