To troubleshoot a CD/DVD drive not recognizing tray:

1. Check if the disc tray is completely closed and if the tray is empty. If the drive still does not recognize it, try opening and closing it several times, so that the disc can reset.
2. Check if the disc is compatible with the optical drive by checking the disc manual or media site.
3. Clean the disc and inspect it for any visible defects. Dirt or dust particles, too many scratches, a warped disc, or fingerprints can prevent the drive from recognizing a disc.
4. Check the Volumes/Disk Manager and see if the drive is recording the disc. If the disc is recognized, but it is still not working, we recommend checking the cables or replacing them.
5. Run the diagnostic tool that are provided by the manufacturer on the optical drive. Your manufacturer might be know about any issue concerning the drive.