On the server 'pkfl335mesmgmt1', run
cd \Program Files\Omniback\bin
devbra -dev
This will show a list of all SCSI-attached devices, including SAN-connected devices. Some may show their serial numbers as 'N/A', some my show either no SCSI paths or incorrect SCSI paths from how the device is configured in Data Protector
When you access any device in DP, the first thing that happens, in the Background, is to run the 'devbra -dev' to compare serial numbers, and the SCSI paths to see what is configured, and this is what si failing