problem adding new host from different network with the zabbix server

[bigzhia]

dear all, im still new in zabbix

i already success install zabbix server in centos 5.8
i have no problem adding server host weather is linux server or windows server
and i dont have any problem adding mikrotik router host as snmp host

but i do have problem here when im trying to add one linux server host, a OpenVPN server base on ClearOS 5.2, in different network with the zabbix server..

my zabbix server ip : 172.16.99.7 - 172.16.99.0/24
and my OpenVPN server ip : 172.16.98.51 - 172.16.98.0/24
the network connect by mikrotik router, i have masquerade all network trafic between those network, so practicaly i can ping zabbix server from openvpn server, so do form openvpn server to zabbix server

but still it not working
hope somebody can help my to figure it out the problem
*sorry if my english not good enough


here is server log

17307:20121121:152412.861 Zabbix agent item [agent.ping] on host [vpn.terminix.co.id] failed: first network error, wait for 15 seconds
17314:20121121:152427.258 Zabbix agent item [system.cpu.load[percpu,avg1]] on host [vpn.terminix.co.id] failed: another network error, wait for 15 seconds
17314:20121121:152442.278 Zabbix agent item [system.cpu.util[,idle]] on host [vpn.terminix.co.id] failed: another network error, wait for 15 second
17314:20121121:152457.301 Zabbix agent item [system.cpu.load[percpu,avg15]] on host [vpn.terminix.co.id] failed: another network error, wait for 15 seconds
17314:20121121:152512.325 temporarily disabling Zabbix agent checks on host [vpn.terminix.co.id]: host unavailable

and here is the agent debug mode log

25469:20121121:142707.996 Starting Zabbix Agent [vpn.terminix.co.id]. Zabbix 2.0.3 (revision 30485).
 25470:20121121:142707.996 agent #0 started [collector]
 25471:20121121:142707.997 agent #1 started[listener]
 25472:20121121:142707.999 agent #2 started[listener]
 25473:20121121:142707.999 agent #3 started[listener]
 25472:20121121:152031.650 Got signal [signal:15(SIGTERM),sender_pid:28195,sender_uid:0,reason:0]. Exiting ...
 25473:20121121:152031.650 Got signal [signal:15(SIGTERM),sender_pid:28195,sender_uid:0,reason:0]. Exiting ...
 25469:20121121:152031.651 One child process died (PID:25472,exitcode/signal:255). Exiting ...
 25469:20121121:152031.651 Zabbix Agent stopped. Zabbix 2.0.3 (revision 30485).
 28206:20121121:152031.766 Starting Zabbix Agent [vpn.terminix.co.id]. Zabbix 2.0.3 (revision 30485).
 28206:20121121:152031.767 In init_collector_data()
 28206:20121121:152031.767 End of init_collector_data()
 28207:20121121:152031.767 agent #0 started [collector]
 28207:20121121:152031.767 In init_cpu_collector()
 28207:20121121:152031.767 End of init_cpu_collector():SUCCEED
 28207:20121121:152031.767 In update_cpustats()
 28207:20121121:152031.768 End of update_cpustats()
 28208:20121121:152031.768 agent #1 started[listener]
 28210:20121121:152031.770 agent #3 started[listener]
 28211:20121121:152031.770 agent #4 started [active checks]
 28211:20121121:152031.770 In init_active_metrics()
 28211:20121121:152031.770 Buffer: first allocation for 100 elements
 28211:20121121:152031.770 In send_buffer() host:'172.16.99.7' port:10051 values:0/100
 28211:20121121:152031.770 End of send_buffer():SUCCEED
 28211:20121121:152031.770 refresh_active_checks('172.16.99.7',10051)
 28209:20121121:152031.771 agent #2 started[listener]
 28211:20121121:152031.771 Sending [{
        "request":"active checks",
        "host":"vpn.terminix.co.id"}]
 28211:20121121:152031.771 Before read
 28211:20121121:152031.941 Got [{
        "response":"failed",
        "info":"host [vpn.terminix.co.id] not found"}]
 28211:20121121:152031.941 In parse_list_of_checks()
 28211:20121121:152031.941 In disable_all_metrics()
 28211:20121121:152031.941 No active checks on server: host [vpn.terminix.co.id] not found
 28211:20121121:152031.941 In process_active_checks('172.16.99.7',10051)
 28211:20121121:152031.941 End of process_active_checks()
 28211:20121121:152031.941 In get_min_nextcheck()
 28211:20121121:152031.941 Sleeping for 1 second(s)
 28207:20121121:152032.769 In update_cpustats()
 28207:20121121:152032.769 End of update_cpustats()