I guess that I experienced the same situation. In fact, my mother board has 2 SATA slots but I'm using them for hard drives. Then I've got that SATA drive and had to install an PCI adaptor which has 2 more SATA slots. At first, I got the same situation like you described as my computer did not recognise the drive at all. Then I found a CD that go with the adaptor and install its driver (RAID driver). Do your adaptor have driver? If yes, try to install it and see how it go.
Hope this help.