WithName() allows you to assign a name to an expression.
So, in that case, date and group hold the single value of the iteration (in order to avoid currentValue override in nested the loops, like this one).
I fixed your button: now it should work.
Let me know if this is the desired outcome.
Cheers!
You have helped me a lot and not for the first time!
Thank you very much! Special thanks for the quick responses!!!
Now I understand how “withName” works.