1. Click the configuration tab
2. Click SNMP Monitor Wizard
3. Type in the IP address of the system in the section "IP address or hostname:"
4. Change the Community as needed
5. Enter 188.8.131.52.4.1.3184.108.40.206.3.2.1 for the OID
6. Click Next
You should get back a result
I was able to add the OID and get it working following your method.
For upcoming ipMon nub like I am and having similar issue - there were few more steps involved after bkyle's excellent description.
That was choosing "select" button from SNMP Scan Result page to follow through and defining few parameters over next 2-3 pages.