Add second disc to PR4100, power supply?

I just bought a second 10TB harddrive. But the LED is always Red in that bay. If I go to configuration I can see the drive in the disc status. But I cant initialize it in the RAID options. Do I need a second power supply? If so, I hace this one, but I don´t think it is compatible because of the 5.5mmx2.5mm. What to you recommend? What are the exact specs of the original power supply? Cant find it on WD website