Introduction
Having syntax errors, or incorrect references in your zone files can cause PowerDNS/BIND to not load the zone.
Procedure
Finding the error for the zone that is not loading can be performed simply by running this command and specifying for the domain you are having issues with. This will return an error if a problem is present.
domain="domain.tld";named-checkzone $domain $(grep -Rl "$domain" /var/named/|grep -v "/var/named/cache/")