New Tape Drive Appears as a Standalone and NOT as Part of Robotic Library

We have a Dell/EMC ML3 Tape Library. It came with one drive. It is connected from the tape drive SAS Port 0 to a controller card in the Windows Server using a SFF-8644 to SFF-8088 cable. In BackupExec, in Storage, it shows the Robotic Library, and it shows the tape drive under it correctly. This all works fine.

We just bought a second tape drive for redundancy. Installed that into the tape library, and the library sees it and shows 2 drives. Attached the new tape drive's SAS Port 0 to the same controller card in the Windows Server using an additional SFF-8644 to SFF-8088 cable.

I see both tape drives in Windows Device Manager. However, in BackupExec, in Storage, it shows the new tape drive as a standalone drive. It will not use the robot to load tapes into it.

Do I need to attach the second drive in a different way? Do I need to change something in the ML3's Management GUI? I am wondering if I should be using a SFF-8088 to SFF-8088 cable to chain the new tape drive's SAS port 0 to the original tape drive's SAS port 1?

Thank you!