Problem with SELECTEDVALUE

Hi

I have a simple data table with years (Anno) ranging from 2021 to 2023

I have created two tables just with the list of years

f_start = summarize(Dati,Dati[Anno])

f_end = summarize(Dati,Dati[Anno])

I want to create a table like this

Where, corresponding to each Segment, I have the sum of all the values from the selected Start year and from the End year

Now, if I build a new table like the following it returns me a blank table:

TabStarEnd =
var s_start=selectedvalue(f_start[Anno])
var s_end=selectedvalue(f_end[Anno])

return
ADDCOLUMNS(    
    SUMMARIZE(
        Dati,
        [Segmento]
    ),
    "Start",CALCULATE(
        SUMX(filter(Dati,Dati[Anno]=s_start),Dati[Ordinato])
    ),
    "End",CALCULATE(
        SUMX(filter(Dati,Dati[Anno]=s_end),Dati[Ordinato])
    )
)

Instead, if I force "2021" and "2023" in s_start and s_end respectively it works (and gives the result I have shown before)

Why is function SELECTEDVALUE not working?

Thanks

Fabrizio