Won't read 2 cd drives

I have an old Dell Dimension 2350 and it came with a dvd-rom and a cd burner. A few days ago it stopped showing both drives in windows. I have tried putting new drives in but the only way windows will read either is if only one is plugged in. If i remove the ide cable from the cd then it will show the dvd and vice versa. If both are plugged in then neither shows. If anybody has any ideas please help me out his is frustrating as heck. the new dvd is a burner.

 

Have you checked the jumper settings to make sure that they are configured correctly as to master/slave relationship?