Managesieve and virtual users

Hello list,

I'm trying to setup sieve on a Debian 9 install with virtual users. Perhaps I'm getting old, but I can't figure out why managesieve is not working for virtual users. I have about 20 v users on this machine and only one has also a real unix account. The sieve rules work for this single unix account  but not for any other account. I have read tried various HOWTO's found on the net like this :

https://forum.vestacp.com/viewtopic.php?t=11363

but nothing is working for my case, so something is wrong in my setup and I hope you guys might shed some light . The setup is rather simple it's 20 v users with one public folder , I have tried both dovecot lda and lmtp .

doveconf -n  included

Thanks in advance for any help