Verify that the drive backplane is seated properly at the bottom, in the small slot near the DVD drive.
Note - The mini-SAS plug must be inserted into the upper mini-SAS connector on the disk backplane. This short cable connects the DVD to its USB bridge on the motherboard. The longer SAS cable connects drive bays 4 and 5 to a storage device in the rear of the system. The lower mini-SAS connector on the disk backplane requires the standard, four-channel mini-SAS cable for drive bays 0 to 3.
See Install a Drive.
Note - The product serial number used for service entitlement and warranty coverage might need to be reprogrammed on the disk backplane by authorized service personnel with the correct product serial number located on the chassis EZ label.