Thank you for your help, there is no error message now. I can download & use the action.
But now i can test the action, I see it doesn't seem to manage exponents...
Do you know why Jean didn't add it in 2014? (forgotten or technical problems?) Or is there another solution?
I want to be able to use float variables with another variable as exponent... I already managed it with a loop, but I'll have to use it again, and it would be better to be done properlywith a single action, I think.