Have you loaded the MIBs into your OpenView server? You may also need to re-load them if you've upgraded the software on your ONS boxes.
From the 15454 FAQ:
Q. Can I use network manager supplied by any vendor to send and receive SNMP traps from the Cisco ONS 15454?
A. Yes, but the network manager must allow you to load and compile MIBS. You can find the procedure to load and compile ONS 15454 MIBS in Cisco ONS 15454 Reference Manual...
http://www.cisco.com/en/US/partner/docs/optical/15000r9_0/dwdm/reference/guide/454d90_snmp.html#wp48174 lists the MIBs for ONS 9.0 software.
Get the latest MIBs from your installation CD or from http://www.cisco.com/go/mibs
Hope this helps. Please rate the post if it does.