Comment 9 for bug 795239

As commented by OzzyFrank, I get the same error after upgrading to Ubuntu 12.10, eject command worked for years for me.
(The eject command is a must for me in ubuntu, as the hardware button does not work properly (Acer Aspire 5810T)
https://help.ubuntu.com/community/AspireTimeline/Fixes#DVD_Not_Mounted)

Output (spanish)
"eject -V"
eject versión 2.1.5 por Jeff Tranter (<email address hidden>)

"eject" or "eject cdrom"
eject: incapaz de encontrar o abrir el dispositivo para: «cdrom»

"sudo lshw -C disk"
...
  *-cdrom
       descripción: DVD-RAM writer
       producto: DVDRAM GU10N
       fabricante: HL-DT-ST
       id físico: 0.0.0
       información del bus: scsi@4:0.0.0
       nombre lógico: /dev/cdrom3
       nombre lógico: /dev/cdrw3
       nombre lógico: /dev/dvd3
       nombre lógico: /dev/dvdrw3
       nombre lógico: /dev/sr0
       versión: AP03
       capacidades: removable audio cd-r cd-rw dvd dvd-r dvd-ram
       configuración: ansiversion=5 status=nodisc

Workaround: It works for me using "eject /dev/cdrom3"