When you say you are filtering "right at the data source", do you mean you have added a data source filter? And are you using it on the "condition" tab of the filter.
Usually when I create a calc that results in "this" or "that", I put that calc on the filter shelf and select for whichever value I need for that sheet.
But when I create a data source filter, I result in a Boolean value and put it on the "condition".
The attached superstore example has a data source filter using the condition tab. It grabs two specific values. See attached. (Vrersion 8.2 workbook.)
Thanks for coming back so quickly, yes, I'm trying to isolate my population down by using the condition tab on the data source filter. I don't want to use the filter shelf on a worksheet, because I'd like to isolate the correct population down to begin with. I think I can mimic what you have in your example and reflect what I need in terms of criteria, but I'm still looking for an operator that basically denotes 'does not contain', that I can write into my formula.
Try: NOT CONTAINS(...
In the attached, edit the data source filter. Un-comment the last line. You will see that it will take out "South America" from the list it returns.