Issue using fields inside set analysis

[#1]

I have two fields: "KeyDate" and "Chosen Date".  I am trying to make a chart expression that outputs all data for KeyDate<"Chosen Date".  Basically I'd like the user to select a date in a filter pane (Chosen Date), and the chart output all data from the earliest date up until that point.

My current chart expression: This doesn't work.  I have tried with quotes, without quotes, and many different syntax options and it outputs nothing.

     Sum({$<[KeyDate] = {'<[Chosen Date]'}>} Usage)

The same expression works when I input the date num manually.

Sum({$<[KeyDate] = {'<48462'}>} Usage)

If anybody could tell me what I'm doing wrong it would be much appreciated.

[miguelbraga]

Make this change:

     Sum({$<[KeyDate] = {' < & 'num([Chosen Date])' '}>} Usage)

If that doesn't work let me know

Regards,

MB

[#3 · Accepted solution]

Miguel that didnt work. Fortunately I found an expression that worked.

Sum({$<[KeyDate]={'<= $(=[Chosen Date])'}>}Usage)