how to configure iDRAC SNMP trap to OME 2.2

Go to Server, Alerts, SNMP and Email settings, set Destination address as OME (Windows 2012) server.  Also set the community string as the same for SNMP service on OME server.  When clicked on Send to test SNMP trap the screen just refreshed then nothing.  In OME I didn't see any event related to the test and didn't received alert emails.  How does the test work?  How can I tell if iDRAC can send SNMP trap to OME?

Thanks,

David