[Dovecot] dovecot ignores entries in virtual_alias_maps when using dovecot lda

[Marko Weber]

hello list,
i need help. dovecot dont look into my virtual_alias_maps .
i set via postzfixadmin an alias postmaster at domain.tld to 
newmail at domainother.tld.
when i send mails to postmaster at domain.tld mails are rejected. dovecot 
authworker tells
me in log: user unknown.
but i can request the data via postmap -v -q postmaster at domain.tld 
mysql:/etc/postfix/mysql_virtual_alias.cf
and get result "newmail at domainother.tld".

any ideas, hwo to get dovecot to look into my alias maps?

marko