WD My Book Duo (grey) doesn't recognize drives

After original Duo got smoked by lightning, I purchased an empty My book Duo external (grey) Raid box, along with two 3 TB WD Red drives. The Duo does not recognize the drives in anyway, doesn’t even spin them as far as I can tell. Both drives mount and act perfectly when installed in a HDD dock. My iMac does have WD security and drive utilities installed, and it does recognize the My Book Duo. Any ideas would be greatly appreciated!