(Everyone: sorry to reply here, but I couldn't find an email address for Nick, who posted a rating earlier today...)
Nick, please post bug reports at rt.cpan.org, not cpanratings.perl.org. From your brief description of the problem, it appears that you are passing a net mask to the match_ip(), which expects a single IP addresss. That is, you have called "match_ip('192.168.0.0/24', $re)" when you should have called "match_ip('192.168.0.4', $re)". The documentation states that match_ip expects "...a single IP address as a string of the form C<aaa.bbb.ccc.ddd>...". The docs also say "WARNING: This function does no checking for validity of the IP address."
If you have any further problems, please contact me offline. Net::IP::CMatch is a very nice alternative to this module, but for matching against a large set of IP ranges, my module is actually faster, thanks to Perl's powerful regexp engine.
I could not get this to work properly. When adding a network IP adress, I got errors like 'Argument "0/24" isn't numeric in pack at /usr/local/share/perl/5.8.4/Net/IP/Match/Regexp.pm line 209.'. The documentation does not appear to show a solution - unless I'm missing something :)