[Dirvish] expire rule doesn't work as desired

[Norman]

Hi there,

i've tried several times to change the expire rules to my needs. But 
unfortunately none of the approches worked and now i'm total confused. I 
highly appreciate any hints. So, here's my setup:

master.conf:
expire-rule:
#       MIN HR    DOM MON       DOW  STRFTIME_FMT
         *   *     *   *         *   +6 hours
         *   00    *   *         *   +7 days
         *   00    *   *         1   +4 weeks
         *   00    1   *         *   +2 months

/etc/cron.d/dirvish
# run every 2 hours
0 */2 * * * root /etc/dirvish/dirvish-cronjob

/etc/dirvish/dirvish-cronjob
/usr/sbin/dirvish-runall --quiet && /usr/sbin/dirvish-expire --quiet


My desired expire rule is,
that the backups made every 2hours expiring after 6 hours,
that the backups made at midnight been kept for 7 days,
these who are made on first day of week expire after 4 weeks.
At last the backups made on first day of month expire after 2 months.

My dir listing (yyyy-mm-dd-hh):
2015-07-01-00
2015-07-19-00
2015-07-26-00
2015-07-28-00
2015-07-29-00
2015-07-30-00
2015-07-31-00
2015-08-01-00
2015-08-02-00
2015-08-03-00
2015-08-03-14
2015-08-03-16
2015-08-03-18
2015-08-03-20
2015-08-03-22
2015-08-04-01
2015-08-04-03
2015-08-04-05
2015-08-04-07
2015-08-04-09
2015-08-04-11
2015-08-04-13
2015-08-04-15
2015-08-04-17
2015-08-04-19
2015-08-04-21
2015-08-04-22
2015-08-05-01
2015-08-05-02
2015-08-05-04
2015-08-05-06
2015-08-05-09
2015-08-05-11
2015-08-05-13
2015-08-05-15
2015-08-05-17
2015-08-05-18
2015-08-05-20
2015-08-05-22
2015-08-06-00
2015-08-06-02
2015-08-06-04
2015-08-06-06
2015-08-06-09
2015-08-06-11
2015-08-06-12
2015-08-06-14
2015-08-06-16
2015-08-06-18
2015-08-06-20
2015-08-06-22
2015-08-07-00
2015-08-07-02
2015-08-07-04
2015-08-07-06
2015-08-07-09
2015-08-07-10
2015-08-07-12
2015-08-07-14

Thanks in advance!
Norman