Trying to add CD-W to tower can’t!!!

I’ve done this 1000 times but can’t figure this one out. I’m trying to add a CD-Writer to a Dell. The Dell currently has a cd-rom, zip drive, and floppy drive. When I physically installed the CD-Writer it didn’t recognize it. Put the ribbon fromthe cd-rom to it, didn’t work. I tried all possible ways to connect it and I can’t get all the drive to work. HELP!!!