How to get the bar chart variable factors changed by filter selection ( GetFieldSelections())?

[nezuko_kamado]

I'm trying to create a bar chart that changes variable factors by filter selections.

With ID of A, B, and C, I want to compare two selected factors' sum

like  A&B sum by date,   A&C sum by date , or B&C sum by date as below.

 

But the first issue I'm facing is sum({$<ID={'$(GetFieldSelections(ID))'}>} Unit) does not bring sum unit into the graph, even though KPI shows the selected factor. 

Then the second issue is that how can I apply two selections into that one bar chart? 

data is as below.

original:
load * inline [ Date, Week, ID, Unit
9/1/2021, 1, A, 1
9/1/2021, 1, A, 2
9/2/2021, 1, A, 1
9/2/2021, 1, A, 2
9/2/2021, 1, C, 2
9/3/2021, 1, A, 1
9/4/2021, 1, A, 2
9/5/2021, 1, A, 2
9/6/2021, 1, A, 2
9/7/2021, 2, A, 3
9/9/2021, 2, A, 3
9/9/2021, 2, A, 3
9/9/2021, 2, C, 3
9/3/2021, 1, B, 1
9/4/2021, 1, B, 2
9/5/2021, 1, B, 2
9/6/2021, 1, B, 2
9/7/2021, 2, B, 3
9/7/2021, 2, B, 5
9/7/2021, 2, C, 5
9/9/2021, 2, B, 3
9/10/2021, 2, A, 3
9/14/2021, 3, A, 2
9/10/2021, 2, B, 3
9/11/2021, 3, B, 2
9/12/2021, 3, B, 2
9/13/2021, 3, B, 2
9/13/2021, 3, B, 4
9/14/2021, 3, B, 2
9/27/2021, 5, A, 2
9/28/2021, 5, A, 5
9/15/2021, 3, B, 2
9/15/2021, 3, B, 3
9/16/2021, 3, B, 2
];

[PrashantSangle]

user double quote and = to evaluate your expression within set analysis like

sum({$<ID={"$(=GetFieldSelections(ID))"}>} Unit) 

also try with concat()

Regards,

Prashant Sangle

[nezuko_kamado]

Great it works! And could you help me for the second question please?

So, how can I make two selections of IDs compose two bars side by side? something like,  GetFieldSelections(ID)[1] goes to the first graph, and GetFieldSelections(ID)[2] goes to the second graph.

So that I can comepare like  A&B.   A&C, or B&C  side by side from graphs. Is this possible?

Thank you so much.