SpamAssassin Problems

Hi Everyone! I'm relatively new to WHM and CPanel, and have it installed on a VPS that I use to administer a handful of domains. I am experiencing a problem with activating SpamAssassin, though (it is quite important to have activated since almost all of the domains are receiving spam on a daily basis). When I try to activate it in CPanel, it activates but with the following message:
config: no rules were found! Do you need to run 'sa-update'? at /usr/local/cpanel/3rdparty/perl/514/bin/spamassassin line 407
I looked it up, and most sources just suggested that I run sa-update from the command line:
root@ruan [~] sa-update -bash: sa-update: command not found
So then I tried:
root@ruan [~]# /usr/local/cpanel/3rdparty/perl/514/bin/sa-update channel: no 'mirrors.updates.spamassassin.org' record found, channel failed
Still no luck. I am at my wits end, as I really need this to work. Do you maybe have any suggestions for me? Thanks, Ruan