PowerDNS - TXT records not being served for 1 domain

Hi,

I've got 4-5 domains in my PDNS setup. If I create a TXT record for 4 of them and do a dig @ns1.mydomain.com TXT mydomain.com then I get a reply back with the relevant TXT records.

With the last domain I get no answer back as to the TXT records, it's just blank.

I've restarted the PDNS service - any way I can troubleshoot this? Has anyone had anything similar?

Thanks,