Its a problem with SNMP v1. It is fixed for SNMPv3. But you should be having SNMPv3 trap server in your environment.
Here is the work around If you are using SNMPv1.
1) Boot OCUM appliance into shell prompt. How? Login to the ESX vcentre where VM resides. Take a snapshot of the VM. Proceed to launch console from vcenter. Give admin/your_password. Go to option 4 ) Support/Diagnostics, type 'erds' in the section asks for 'Enter your choice:'. It will ask you to enter password. Set a password. Access will be enabled only for the first terminal session. 2) Login to the cli by giving username as 'diag' and the password you set above. 3) Note the IP address of the OCUM from 'sudo ifconfig' 4) edit /etc/hosts file with vi or nano 5) Set host file as below. 127.0.0.1 localhost <ip address of the ocum> <hostname_with_fqdn> <hostname> ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters 6) Reboot the ocum server. 7) Try sending alerts now. Try disabling ipv6 settings in /etc/hosts file if that's still not working.