The command line looks OK and seems to be working - it is returning the statistic for the host. However, the NSCA support is only for GUEST data, not for host/cluster/datacenter data.
You can add the '--debug 1' option to get some progress info as it runs.
You can omit the --hostname option. In this case, you'll get info for ALL guests sent to the NSCA server.
You can look at your NSCA logs on the Nagios server to see what is coming in, and external command logs in the nagios log. You may need to use --canon, --tolower and --nscastrip to convert a FQDN to the guest hostname as use in Nagios.
I'm currently working on a new, completely passive agent to monitor VMWare via the API for Nagios and MRTG. This will give passive status info for all things (including hosts, clusters, datacenters) and will dynamically create config files if required. However it is some way off operation at the moment.
UNIX Systems, ITSS, University of Auckland, NZ
Woe unto them that rise up early in the morning... -- Isaiah 5:11