Some registrars, particularly Network Solutions, offer poor support for DNSSEC records, or anything beyond A and CNAME records really. For a long time it was officially unsupported; lately there is a footnote at the bottom of the advanced DNS options page to call tech support if you want to discuss using DNSSEC---although they'll happily sell me an extended validation certificate....
I run my own DNS server. I contacted my registrar to enable DNSSEC for my domain on the domain root server. All they could give was a package where they would take over my domain hosting, that was the only way to get DNSSEC for my domain. Switching registrars next year when my domain expires .. can anyone recommend one that actually supports DNSSEC for .info domains with private key management?