The configuration of the queue in both the logmon probe and the hub looks good. You can probably confirm that by looking at the Status tab in the hub GUI (if you have not already). The logmon probe should be connected to your Inmage queue, and if any SNMP traps have been received, the queue counters should indicate that. My main concern was that the right messages are going into the queue.
If I recall correctly, when the logmon probe is configured to monitor a queue, it looks for a field named message in each message from the queue. I am guessing the SNMP-TRAP messages do not have a field named message. It probably uses some set of fields to capture the individual fields in the trap rather than combining them into a single text string. Just guessing though. You can check the behavior by using DrNimBUS to sniff the messages on the message bus.
It might work better to configure the snmptd probe to log the traps to a file. I believe that option puts the traps into a trap.log (or traps.log) file in the snmptd probe directory. Then you could monitor that with the logmon probe. (I really prefer your idea of using a queue rather than a log file, but it looks like the two probes probably lack sufficient options to make then work well together.)