Computer Does Not Recognize Second Cd Drive (Vista Machine) System Does Not Detect Dvd/cdrom Drive

I had put a second cd drive into my computer so I can make cds with it. I don't want to burn too many on my master drive, so that way it wont burn it out. So I put the second one in, the computer will not read either drive. So when I unplug it, then the main drive shows up. Know what it could be? I am on Vista... On other computers I always had two and never had this problem. I went to my computer and there was no icons there for the drives.