Add external drive to HR24

I have a new HR24-500 HD DVR.  I connected a Western Digital My Book AV DVR Expander (WDBABT0010HBK-NESN) to the eSATA port with the power cord disconnected from the HR24.  I first powered up the external drive, the powered up the HR24.

After the HR24 powered up, the playlist shows recordings on the internal drive, which indicates to me that the external drive is not being used.

Does the HR24 not support adding external drives?

100 hours of HD on the internal drive is nice, but with series recording and On Demand, I wanted to expand to 200 hours of HD on the 1TB external drive.

Please advise.