The zone file is entirely correct as far as syntax goes and was updated with the new record without error. The new record does not appear in queries about it, but does appear in the new zone file even on the secondary servers.
“Re: A hard DNS problem [1]”
Ah, there's more information about the problem. I did mention [2] that “[i]f the record does show up, then it's a propagation issue, maybe related to caching or TTL (Time-To-Live) issues.” But to be fair, there could be a few other issues. I don't think it's an issue of the zone file was updated but the DNS (Domain Name Service) servers weren't restarted—I don't get that from the wording, and there's a quick test for that anyway—check the serial number by requesting the SOA (Start of Authority) RR (Resource Record).
Another issue to check is what the root DNS servers think the authoritative DNS servers for the zone are. A quick check of whois could provide that information, or even a query outside the network for the NS (Name Server) RR for the domain. If they don't match the expected list of DNS servers, then either the domain expired, was transfered, or someone else in the organization updated the NS records for the domain.
But if the NS RRs are correct, and I can see the proper serial number from an SOA query from outside the network, but not the new record … I don't know. I might try to use a few different locations outside the network to do queries from, just to make sure it's not the DNS server I'm using for queries, but if they all exhibit the behavior … I doubt it'll be an unsupported RR type, perhaps something to do with DNSSEC (Domain Name System Security Extensions )? Which is beyond my paygrade …
I would like to know the actual issue is—I can see it either being something very trivial and I'll kick myself not not seeing, or it's something that I've not had experience dealing with at all.