não é capaz de montar o sistema de arquivos ISO9660 antes de ejetar e reinserir a mídia

Question

Depois de gravar um sistema de arquivos ISO9660 ( wodim -v dev='/dev/scd0' -sao ubcd521.iso ) em um CD, eu sempre preciso primeiro ejetar o CD e reinseri-lo novamente para poder montar o CD criado :

root@T42:~# file -s /dev/sr0 
/dev/sr0: data
root@T42:~# mount -t iso9660 /dev/sr0 /media/
mount: block device /dev/sr0 is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/sr0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

root@T42:~# eject
root@T42:~# #re-inserted CD tray
root@T42:~# file -s /dev/sr0 
/dev/sr0: ISO 9660 CD-ROM filesystem data 'UBCD521                        ' (bootable)
root@T42:~# mount | grep cd
/dev/sr0 on /media/cdrom0 type iso9660 (ro,noexec,nosuid,nodev,user=usr)
root@T42:~# 

Estou apenas imaginando o que causa isso?