I tried adding a WD My DVR Expander to my Scientific Atlanta 8300HDC box which recently upgraded to Navigator. I attached the DVR Expander and rebooted. However, when it says "Attention! This drive is not formatted. Please press A key to reformat the drive or C key to exit," I pressed A but the message kept coming up and would not reformat. So my question is, how do I reformat it on my DVR? I went to Device and it doesn't say anything about setting up additional hardware like a TiVo would. What can I do?