Question to solve a "invalid error name", into a expression formula

Dear community, I have a litte problem with a formula into a Expression.

I can’t understand what the error may come from: (74.9 KB)


Here something working. Not sure where it was wrong as there were many errors. I change brackets to parenthesis as it seems there are used for unitize expression. The multiplication was an X. You also inputted string so it is better to explicitely convert to double. So you can see if there are errors. (77.8 KB)

Thanks for the help Laurent.