last command displays non-current logins

I have had some problems with a hacker. I am trying to track the logins to my system. However, 'last' gives me a return that states the latest login was Dec 17th (even though I loginto the system multiple times per day. Any idea how I can 'restart' the recording of logins?
[298 byte] By [haplo62] at [2007-11-25 23:19:43]
# 1
Look for /var/adm/utmpx and wtmpx, when you reboot the system it kicks off /etc/init.d/utmpd should have a sym link to /etc/rc2.d/S88umptd, have u rebooted your server?
danzak1 at 2007-7-5 18:07:48 > top of Java-index,General,Talk to the Sysop...