Need help with Dax

Hi,

Please check the below picture and the attached pbix file.

Customer count: = 
VAR _sourcecount =
    COUNTROWS ( DISTINCT ( Source[Source] ) )
VAR _selectedsource =
    DISTINCT ( Source[Source] )
VAR _nonselectedsource =
    EXCEPT ( ALL ( Source[Source] ), _selectedsource )
VAR _customerstable =
    ADDCOLUMNS (
        Data,
        "@sourcecount", COUNTROWS ( FILTER ( Data, Data[Customer] = EARLIER ( Data[Customer] ) ) )
    )
VAR _customerlist =
    SUMMARIZE (
        FILTER ( _customerstable, [@sourcecount] = _sourcecount ),
        Data[Customer]
    )
VAR _exceptcustomerlist =
    SUMMARIZE (
        FILTER ( ALL ( Data ), Data[Source] IN _nonselectedsource ),
        Data[Customer]
    )
VAR _expectedcustomerlist =
    EXCEPT ( _customerlist, _exceptcustomerlist )
RETURN
    COUNTROWS ( _expectedcustomerlist )

Customer sales expected result: = 
VAR _sourcecount =
    COUNTROWS ( DISTINCT ( Source[Source] ) )
VAR _selectedsource =
    DISTINCT ( Source[Source] )
VAR _nonselectedsource =
    EXCEPT ( ALL ( Source[Source] ), _selectedsource )
VAR _customerstable =
    ADDCOLUMNS (
        Data,
        "@sourcecount", COUNTROWS ( FILTER ( Data, Data[Customer] = EARLIER ( Data[Customer] ) ) )
    )
VAR _customerlist =
    SUMMARIZE (
        FILTER ( _customerstable, [@sourcecount] = _sourcecount ),
        Data[Customer]
    )
VAR _exceptcustomerlist =
    SUMMARIZE (
        FILTER ( ALL ( Data ), Data[Source] IN _nonselectedsource ),
        Data[Customer]
    )
VAR _expectedcustomerlist =
    EXCEPT ( _customerlist, _exceptcustomerlist )
RETURN
    SUMX (
        FILTER ( Data, Data[Customer] IN _expectedcustomerlist ),
        Data[SalesAmt]
    )