switch depending on the slicer selection

Hi Anonymous  thank you very much for your reply and sorry for not answering you before, but I've been travelling with no Access to my computer.

I have tried your formula but I think that I am doing something wrong.

Here you Will find a simplified pbix of my model test target 

Just a Little bit more information:

Table 1 (Targets) : Contains water consumption targets by site code and date.

Date: is the first day of the fiscal year. The target applies for the whole year.

Site code: 99 is a ficticia code, which represents the total company but its not the sum of the individual sites

Table 2 (Sites): Site code and site name

You Will notice that 99 is not in the table. Why? It is a direct query from OCDB so only contains the real sites.

So what I want do do is:

If I select an individual site with the slicer, then return the target for this site: Example: 2020, Site 1 -> 3,0987

If I select all sites, the return the target allocated in 99: Example: 2020, Sellected All -> 2,376

Thanks again for your help