I needed to copy a powermail form to another page in a TYPO3 site and change it minimally to adapt it to its new location. After copying the form and its associated page, I renamed one of the form fields and wondered myself why that form field did not appear under its new name.

As it turns out, the variable name of the field is only determined once at creation by powermail and needs to be changed manually after the field has been copied over to a new place.

Now everything works out as intendend!