DAX IN Operator not working as expected

Hi there,

I'm trying to create a status flag based on union values of source and destination. For some reason IN operator is not working as expected. Not sure where im missing.

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Status = 
--gets list of values from column Source & Destination
VAR _COL1 = CALCULATETABLE(VALUES('Table'[Source]),LEN('Table'[Field])>0,'Table'[Source]<>"")
VAR _COL2 = CALCULATETABLE(VALUES('Table'[DESTINATION]),LEN('Table'[Field])>0,'Table'[Destination]<>"")
--unions the list of value of source and destination
VAR _UNION = DISTINCT(UNION(_COL1,_COL2))
VAR _result = IF ('Table'[AllAirports] IN _UNION, "Field Available","No Field")
RETURN _result

Thanks