I simplified the expression by changing your loadscript to simply create a field as part of the load that was your Month and Year.
Date(monthstart(OpenDate), 'MMM-YY') as MonthYear,
FROM [lib://Queries/CallData.xlsx] (ooxml, embedded labels, table is Sheet1);
Then your chart expression is a little simpler to follow:
I've attached my modified version of your application.
Hope this helps. For anyone reading the formula and asking "what in the world is that AGGR stuff" ... be sure to watch this recorded webinar that explains the AGGR function in detail. http://event.on24.com/wcc/r/1282824/3F17A1A59D58CCBE5B9A246A6208176B it includes beginning and intermediate content from me, and advanced content by troyansky
aaaWayne.qvf 192.0 K