Blocking Multiple IP Addresses

[PTS]

I'm having issues blocking a few spammer IP addresses from accessing the websites on my server.

In the Plesk Firewall Module, I setup a rule as follows:

Deny incoming from XXX.XXX.XXX.XXX, YYY.YYY.YYY.YYY on all ports

This used to work for me (on older Plesk version) but for some reason these spammers are still getting through to the sites.

Any ideas or recommendations?

Thanks in advance!