domain name system - DNS problems : correct nameserver, namserver working, but not resolving

My problem is as follows. Any suggestions are welcome.

[domain].org is not resolving

whois and checking the registry information shows that the correct nameserver is set.

The primary nameserver is also the server on which domain.org is hosted.

The primary nameserver is also used for a number of other domains, and is working fine for those.

Logging into the server, I can ping [domain].org and it resolves correctly.

Setting the nameserver as my own DNS server on my laptop, and the URL resolves correctly.

If the domain has the correct nameserver set, and the nameserver can resolve the URL to the correct IP address, and if I use the nameserver as my DNS then it resolves correctly, AND the nameserver is used for other domains which are resolving correctly, then why isn't it working?

NB : this is a new domain registration and has been set up for around 10 days now, so it's not simple slow propagation.

Any ideas?

thanks