IDE Hard Drive not detected.

I have a Compaq Pentium 450 Windows 2000 Server. It has 4 Scsi drives connected to the onboard Adaptec SCSI controler. There is also a SCSI CD Rom, and a floppy drive.
The board has two IDE plugs (Not Used).
I’m trying to install a new Western Digital 80 GIG Hard drive, but it is not being recognized. I have gone into the BIOS setup and set it to auto detect the Hard Drive and also used the Hard Drive diagnostics floppy, but it still can not detect the drive?
I looked on Device Manager, but see no conflicts? Help…