no graph data received

hi everybody,

I followed this url [1] and I have added just a server to test the
monitoring
Actually after 15 minutes I can't see any graph

Some detail:
CentOS 6.4 x32
Cacti 0.8.8b (epel repository)
rrdtool 1.3.8-6

In device's section the status of machine is alway "unknown"
but if I explore

monitoring.x.local (172.16.x.x)
SNMP Information
*System:*1:56:33:UTC:2014:I686
*Uptime:* 92545 (0 days, 0 hours, 15 minutes)
*Hostname:* monitoring
*Location:* Unknown
*Contact:* root@localhost



How can I fix it?
Thanks in advance

Regards


[1]
http://www.tecmint.com/install-cacti-network-monitoring-on-rhel-centos-6-3-5-8-and-fedora-17-12/
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