How can i substrack selection to another value in a graph

[Cap_study]

Hi,

I would like to make a custom curve graph containing prices at specific date, for specific Product. When you select one or multiple Product curve and apply the filter selection, all other are summed to make some kind of Selection vs Sum(other) graph.

To do that, I have prepared two tables:

[Invoice]:
LOAD
[Billing_Date],
[Prod_Hier_Desc],
[TOT_Invoiced]
FROM [lib://DataFiles/Invoice.qvd]
(qvd);

[Sum_invoice]:
Load
[Billing_Date] as [Date],
Sum([TOT_Invoiced]) as Invoice_Total
Resident Invoice Group by [Billing_Date]

I'm pretty sure my problems comes from the fact the Invoice and the Sum_Invoice table have their own date row. What would you recomend to acheive this Selection vs Sum(Other)?

In the graph with dimension Date, i tried to set as mesure:

Sum(Invoice_Total) -  Sum({$<Billing_Date=Date,Prod_Hier_Desc=$(=GetFieldSelections(Prod_Hier_Desc)}>}TOT_Invoiced)


Doesn't seem to work. What am I missing here please ?