Debian - auth.log missing from /var/log

I am learning Debian on RaspberryPI. I've installed 'logwatch' and 'fail2ban' recently and those two were working Great! A few days ago I've spotted that I don't have a file "auth.log" but I do have "auth.log.gz1" etc. (so archive data) I've used command: touch auth.log to create this file, than chown root:adm to change its premissions. However this file is still not working - I can't see any entry in to for the last 2 days even if I was loging in trough SSH. Can you advise: 1. why this file is gone? where to look for a reasons? 2. how to fix the issue, so all my SSH connections (and attacks) will be recorded? PS. pi@pi ~ $ uname -a Linux pi.local 3.10.25+ #622 PREEMPT Fri Jan 3 18:41:00 GMT 2014 armv6l GNU/Linux