Cannot use Singers CDG's

[kenng]

I have Hoster 3.110 and just finished a set of shows for campers. I have an external Plextor hard drive from MTU attached. When I try to use a singers' CDG I get an error message saying either "drive not ready" or "Cannot read disc". I tried many different labels from different singers with no luck. Finally I just hooked up a JVC Karaoke set with an A/B switch. What am I doing wrong?? I know that the drive works because I used it for the last upgrade and it worked fine, not to mention that I used it to originally load the hard drive.