My domain is not resolving without using the `www.`

subdomain.

I can't work out why... here is my current zone file:

```
rcnhca.org.uk 86400 SOA ns0.gradwell.com hostmaster.gradwell.com 2012 10800 3600 604800 86400
*.rcnhca.org.uk. 86400 IN A 195.74.61.93
*.rcnhca.org.uk. 86400 IN MX 10 mail-in-1.lb.gradwell.net.
rcnhca.org.uk. 86400 IN A 195.74.61.93
rcnhca.org.uk. 86400 IN MX 10 mail-in-2.lb.gradwell.net.
rcnhca.org.uk. 86400 IN MX 10 mail-in-1.lb.gradwell.net.
rcnhca.org.uk. 86400 IN NS ns2.gradwell.net.
rcnhca.org.uk. 86400 IN NS ns1.gradwell.net.
rcnhca.org.uk. 86400 IN NS ns0.gradwell.com.
autoreply.rcnhca.org.uk. 86400 IN A 79.135.125.10
autoreply.rcnhca.org.uk. 86400 IN MX 10 mail-in-1.lb.gradwell.net.
list.rcnhca.org.uk. 60 IN A 212.11.71.211
list.rcnhca.org.uk. 86400 IN MX 10 list.rcnhca.org.uk.
list.rcnhca.org.uk. 86400 IN MX 20 mxbackup.gradwell.net.
lists.rcnhca.org.uk. 86400 IN A 193.111.200.31
lists.rcnhca.org.uk. 86400 IN MX 10 lists.rcnhca.org.uk.
localhost.rcnhca.org.uk. 86400 IN A 127.0.0.1
pop3.rcnhca.org.uk. 86400 IN A 79.135.125.10
pop3.rcnhca.org.uk. 86400 IN MX 10 mail-in-1.lb.gradwell.net.
post.rcnhca.org.uk. 86400 IN A 79.135.125.10
smtp.rcnhca.org.uk. 86400 IN CNAME relay.gradwell.com.
```

Can anyone spot why this wouldn't be working?