1.5 Tb My Book not sensed by DVR

I bought a My Book 1.5 Tb external because it had the e-sata port needed to connect to my Scientific Atlanta  8300 HDC DVR. The machine never saw it. Did some research and people say the HDC does not work with extenders. Brighthouse swapped it for the 8300 HD and that is supposed to work with external drives. My drive is still not sensed by the dvr.

I connected the drive to a USB port on my laptop and it’s OK. Any suggestions?