Set Analysis : getting a list of values at a specific date

[simonb2013]

I have a chart in an alternate state, the state is named 'State_Flow'

In that AS chart, I have the following expression:

=count(  { State_Flow<[ID]=[$]::ID , metricID={10}> }  ID )

So I am first limiting my count to those [ID]s selected in the main document.

Then I am limiting the count to [metricID]=10 within the AS set itself.

My problem is thus...

In the first part  [ID]=[$]::ID , I actually only want the [ID]s in the main set at a specific date (which would e the minimum date).

How to say that more clearly ?

- get the IDs from the main document where date=minDate

- for those specific IDs, count the IDs in the AS where metricID=10.

I am really confused as to how modify my expression to acheive this !

Any pointers please ?

many thanks