Can't eject cd magazine - E-99 error message

I can't eject the cd magazine from the cd autochanger Kenwood KDC-C717 (car radio model is KRC-758R). I get an E-99 error message and when I try to eject the cd magazine I only hear a noise but nothing happens.

Thanks I have a Kenwood KDC-C461 6-disc CD changer and can't eject the magazine. I only get a E-99 message and a black lever in the middle of he top seems to only go part way.