The first thing to make sure of when starting you Z-Wave network is what frequency should my device be using in my country.
For New Zealand's the frequency is 921.4 MHz
Its important to make sure that you do get all device on the same frequency so that they will all comunicate with each other.
Also is a legal requirment to only use the correct frequency in your country. New Zealand has a govering body RSM (http://www.rsm.govt.nz/) that make sure you do not use the wrong frequency, so that does not interfer with other devices operating in New Zealand. Large fines can be charged if operating on the wrong frequency.
Sigma Designs Inc, Is the manfacture of the modules that inside most the manfactures products.
The below link is a good source to be able to check for New Zealand Frequency (and other counties if want)
If you have question or thought on this topic, please use this forum link: z-wave-frequencies