Problem with "modify_dns" command

I am trying to use the –remove-record flag for this command as detailed on this page:
http://www.virtualmin.com/documentation/developer/cli/modify_dns

It does not appear to do anything. I am trying to remove an invalid name server from my zone file:

virtualmin modify-dns --domain example.com --remove-record “@ NS 10.8.8.203.”

The above does not do anything to remove the incorrect record.

Hmm, the feature seemed to work fine when I used “Webmin -> BIND -> Update Record in Selected”.