[otrs] logs at location /opt/otrs/var/log

Hi, In my OTRS Config.pm file otrs log location provided is /opt/otrs/var/log/otrs.log But no logs are getting generated. There is a log file at this location but is old -rw-rw-r-- 1 otrs nogroup 5271 2010-02-05 04:40 procmail-2010-02.log No new logs are generated since last restart.If I check with utility *System log* in admin area,i can see some messages. Please suggest what could be the reasons that log file is not generated and how to resolve. Thanks in advance. Regards, Manish Ramteke