Tally number list sums

Hi, I would like to show the sum of values in a number list screen using an Element formula. I assigned each of my 8 number items to Elements (A to H) in the Element Formula layout and used formula “Nbirds+A+B+C+D+E+F+G+H” and with NBirds as the Result Global value. But the formula does not work (always shows 0). In fact just using “A” as a formula and entering a value to the item corresponding to Element A does not show the value. Any insights?

The Elements are not populated until you hit next, so generally you cannot have an Element Formula on the same screen as the number list itself. If you send me a CTX of your app and point me to the screens that are troublesome, I will check it out.