OpManager not polling

I have a trial installation of OpManager on Red Hat 7.3, but it does not appear to be polling SNMP. I observer the following...

- I am able to do a snmpget from the command line using v1 and v2c
- I am able to use the MIB browser
- I am able to look at Asset Details, Installed Software, and Active Process
- I am able to see SNMP request attemps in the log file of a target server
- I am not able to see results from SNMP monitors
- I am not able to test SNMP monitors using the same OIDs I successfully used with the command line snmpget and MIB browser
- The "Last Polled at" line is blank and the "Next Poll at" is in the past