[syslog-ng]group () doesn't work

[syslog-ng@lists.balabit.hu]

Hello,

I am trying to allow group ('it') members to read logs. Therefore I used following
lines:

...
destination hosts {
        file("/var/log/HOSTS/$HOST/$YEAR/$MONTH/$DAY/$HOUR:00"
                owner("root")
                group("it")
                perm(0640)
                dir_perm(0750)
                create_dirs(yes)
        );
};
...

But it doesn't work: new files are in group 'it' but new directories
aren't. What can I do to have newly created directories in group 'it' ?

przemol