new mailbox-users are not added in aliases-file

[Catscrash]

i have a VERY weird problem

when adding a mail user to a domain, the ones with mailboxes aren't in /etc/postfix/ispcp/aliases the ones with forwardings are added just fine

the mailboxes in /var/mail/virtual/domain are created...

how can that be? what can i do against it?
thanks

---

what is even worse: when i manually added everything needed to aliases file and then add / delete another emailaccount in ispcp, everything is gone again...

help please...