[Observium] Adding host problems

hello,

there is someone who can help me please ? when i try to add my host

./addhost.php host.dyndns.org PUBLIC v2c

there is this message

”Trying community PUBLIC ... No reply on community PUBLIC using v2c Could not reach host.dyndns.org with given SNMP community using v2c Trying community PUBLIC ... No reply on community PUBLIC using v2c Could not reach host.dyndns.org with given SNMP community using v2c

Observium v0.11.10.4167 Add Host Tool”

i begin with observium and i have ever added 2 hosts.

thanks,

Simon