OpManager9: Network Interfaces not detected

OpManager9: Network Interfaces not detected

Hi,

I am new to OpManager, current we have a site is using OpMgr9 for servers monitoring, I have few servers can be monitored however unable to detect network interfaces even with Rediscovery... it will shown below message

Unable to rediscover the interfaces.

Possible reasons:
  1. The device is possibly down.
  2. SNMP may not be running in the device.
  3. SNMP parameters may be wrong.
Verified the SNMP services is running fine...

Any idea how to rectify this issue...

Thanks in advanced!

Regards,
Gary