[Dovecot] USERDB environment is unset

[Alex]

Hello,

I tried the v1.0 test of dovecot, because it should make the directories 
for me.
I configured it and installed it. The old one is still there, but I shut 
it down to test the other version.

When I start the new v1.0 test of dovecot i get the following message in 
my log:

Jun  6 13:33:08 APOLLO dovecot: Dovecot v1.0-test72 starting up
Jun  6 13:33:09 APOLLO dovecot: Auth process died too early - shutting down
Jun  6 13:33:09 APOLLO dovecot: auth(default): dovecot-auth: Fatal: 
USERDB environment is unset
Jun  6 13:33:09 APOLLO dovecot: child 18610 (auth) returned error 89

What does that mean?

How can I set this?

Thanks in advance,

Greetings,

Alex