ZBX_NOTSUPPORTED on zabbix wiki examples

[candidinho]

Hello everybody:
I'm new on Zabbix and i have a bit problem.
When i set an userParameter zabbix_get gives me a blank line or a ZBX_NOTSUPPORTED.

I create a simple user parametes with this line in the zabbix_agent.conf:
UserParameter=system.test,who|wc -l
i restart zabbix_agent and i create a new item on the zabbix_server.

Both zabbix_server and zabbix_get( zabbix_get -s 127.0.0.1 -p 10050 -k "system.cpu" ) gives me the same error.
On the logs the zabbix_server says:
Item [Zabbix Server:system.test] is not supported

Zabbix is running on Debian.

Any idea? Thanks.