Sending form to variable mail

Ia had a form in Chrono 5 that took a mailrecepient out of a script

in my debugger the var filled is filled up

[send_mail] => info@mailaddress.be

In chrono 5 i just filled in in Dynamic to: send_mail

But in Chrono 6 there is no dynamic to:

in the body of the mail
i can use: Formulier verzonden door: {data:user_name} voor provincie {data:user_provincie}

But the recipient doesn't work with {data:send_mail} neither with send_mail

nobody ever used this? I can do it in Chrono 5 but not in 6. So i think it is just a little issue of using the wrong syntax.

Ok I finally find out
I had to use a hidden field in between to declare another var.