AuthType Digest: password mismatch

Hello,

I am trying to setup digest authentification with Apache. http.conf
looks like

....
<Directory "/.../private">
AllowOverride None
Order deny,allow
Deny from all
AuthName "private"
AuthType Digest
AuthDigestFile /.../passwd.digest
AuthDigestGroupFile /.../groups
AuthDigestDomain http://server/private/
Require group group1
Satisfy any
</Directory>
....

The file groups exists with the entry

group1: user1

and passwd.digest was created with htdigest. I think the configuration
is correct. However, authentifications fails and the error log shows:

Digest: user user1: password mismatch: /private

Any ideas?

Best
Torsten