you set the master/slave correctly, right? Do you have the latest BIOS? I actually do have a Samsung DVD-ROM set as a master on the second channel of a Promise Ultra100 and it works fine (nothing is slave on that channel). I do notice that if I don't have a CD in the drive, the BIOS screen takes a while trying to find the drive and then doesn't, but as soon as I get into Win2k (server SP-2 BTW) it is listed. I just keep a CD in the drive so the thing boots faster.
So anyway, check your cables and jumpers and make sure you've flashed the latest BIOS. Barring that, try just each drive on its own set as master, and keep discs in the drives. I bet you'll get it to work. If none of that works, it must be an incompatibility between your drives and the card.
Hope that helps.
l2c