Template Not Updating

[kens]

Hi, On Zabbix 1.8.5 I have added an item to a Template, as I have done previously on version 1.6, and I was expecting that item to propagate to the machines monitored using that template. But it doesn't. It does not even show on the monitored items for the specific host. If I add the item directly to the host it works.

Have I missed an important step or misunderstood or stumbled on a problem?

Thanks in advance

Ken