Subdomain delegation not working for external view

[Tom Mikelson]

Problem: Delegations of subdomains do not work in the "external" view.  They
do work in the "internal" view.  For example
the subdomain "bis.mydomain.edu" has been properly delegated to another DNS
in the publicly reachable IP address space of mydomain.edu.
The "internal" clients receive the correct response to a query for "
some-server.bis.mydomain.edu".  The "external" clients receive
"Can't find some-server.bis.mydomain.edu: No answer".  If views are not
implemented all clients receive the correct response.  I am
trying to implement views in order to prevent recursion for clients that are
not part of my domain.
options
{
        version "";
        notify no;
        allow-query { any; };
        listen-on { <public IP address>; };
        directory "/var/named";
};

logging
{
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

view "internal" {
        match-clients { <IP address range of internal clients>; localnets;
};
        recursion yes;
        include "/etc/named.rfc1912.zones";

        //
        // ROOT SERVERS
        //
        zone "." IN {
                type hint;
                file "named.ca";
        };

        zone "mydomain.edu" {
                type slave;
                file "internal/mydomain.db";
                masters { <internal DNS server>; };
                allow-transfer { none; };
        };

        zone "<reverse zone for mydomain.edu>.in-addr.arpa" {
                type slave;
                file "internal/mydomain.rev";
                masters { <internal DNS server>; };
                allow-transfer { none; };
        };

};

view "external" {
        match-clients { any; };
        recursion no;

        zone "mydomain.edu" {
                type slave;
                file "internal/mydomain.db";
                masters { <internal DNS server>; };
                allow-transfer { none; };
        };

        zone "<reverse zone for mydomain.edu>.in-addr.arpa" {
                type slave;
                file "internal/mydomain.rev";
                masters { <internal DNS server>; };
                allow-transfer { none; };
        };
};