Summarize with distinct count

[Ben81]

Hi, 
I have created a measure to do a count of ID for the last time it was modified but I later realised that I need this count to be a distinct count of the ID and I'm struggling with the DAX.  Can anyone help?

Measure =

COUNTX (

    SUMMARIZE (

        'Table',

        'Table'[ID],

        "MaxDate", MAX ( 'Table'[LASTMODIFIEDDATE] )

    ),

    [MaxDate]

)

Thanks,
Ben

[Greg_Deckler]

@Ben81 Try:

Measure =
COUNTROWS
  DISTINCT(
    SELECTCOLUMNS(
      SUMMARIZE (
        'Table',
        'Table'[ID],
        "MaxDate", MAX ( 'Table'[LASTMODIFIEDDATE] )
      ),
      "__ID",[ID]
    )
  )
)

[Ben81]

Thanks mate that worked a treat but can I push my luck a bit more and ask how would that work if I wanted to drop in a USERELATIONSHIP? 

I need to create another measure identical to the above but based on another date field within the same table and both measures are controlled via date slicer.

Thanks