[SOLVED]Understanding Fuel prediction

Hello,

I think I miss something about Fuel prediction.
On A320, after entering a flight plan and click on right arrow from Init page, you enter in Fuel Pred page and click on 2 upper right buttons like here on A330.
Doing this on A320 calculates the needed fuel and then from the refuel popup you can increase/decrease the value and that changes the EXTRA/TIME value accordingly.

On my A330, nothing of that happens; Preselected fuel is too low whatever the value we preselect and EXTRA/TIME remains to 0.

What's wrong please?

Alain