I just bought a new NED ND-3540A DVDBurner. Presently, I have a DVD Drive on the top slot and CD-RW in the bottom slot on my unit. When I tried installing the DVD burner, the system does not recognize the second drive. It will recognize the burner but not the CD-RW. I tried to take out just the DVD player and install the burner but no luck reading it. I took out the burner and replaced it with the orginal drives and the system is now reading both drives. Any idea what i'm doing wrong? I was told it doesn't matter which drive you take out to replace and just remove one of them, and insert the cables the same way. Thanks for any assisntance you can give me.