Error: Cannot open log file '/var/log/nagios' for reading!

I get the error “Error: Cannot open log file ‘/var/log/nagios’ for reading!” when I try to open sections of the Nagios CGI (notifications, Event Log, etc)

I had a look in what I believe to be the directory it is referring to and cannot see the folder /var/log/nagios
Should I create it ? Will it inherit the correct permissions if I do ? (how would I set appropriate permissions ?)

If all of these questions are answered somewhere, would someone mind providing the link please. Thanks in advance

Peco

did you install from RPM or from source?
if you installed from source (recommended) the path should be /usr/local/nagios/var/nagios.log