Quick reverse dns zone question

[Mauricio Tavares]

so I want to define a reverse dns zone to handle 172.16.101.64/27. In
the named.conf file I set:

acl bogusnets {
        0.0.0.0/8;
        1.0.0.0/8;
        2.0.0.0/8;
        192.0.2.0/24;
        224.0.0.0/3;
        10.0.0.0/8;
        !172.16.101.64/27;
        172.16.0.0/12;
        192.168.0.0/16;
};

[...]
// 172.16.101.64/27
// zone "101.16.172.in-addr.arpa" IN {
// zone "64/27.101.16.172.in-addr.arpa" IN {
zone "64-27.101.16.172.in-addr.arpa" IN {
        type master;
        file "/etc/bind/64-27.101.155.216.in-addr.arpa.zone";
};

but when I try to get, say, the fqdn for 172.16.191.84 (using dig or
nslookup pointed at the above dns), I get

Jan 17 15:52:05 mirror named[4078]: client 172.16.101.84#59786: RFC 1918
response from Internet for 66.101.16.172.in-addr.arpa

Since I know that if I use zone "101.16.172.in-addr.arpa" IN { it
works as it should, I must believe it is ignoring my reverse zone and
asking the big wide world to resolve my request. I thought that
starting the zone with either 64-27 or 64/27 would define my
less-than-class-C network (172.16.101.64/27).