There's an issue in APT package manager which is typically origins from /etc/fstab configuration file, it's almost sikt for such a big project like debian !
well, whenever you want to use your source lists, whether cdrom or http sources, there's an issue that would be nasty to you.
the prompt is always show you to add /cdrom .
well, in this point I've seen the /etc/fstab configuration file which has the following content:
# /etc/fstab: static file system information.
proc /proc proc defaults 0 0
/dev/mapper/dhcppc0-root / ext3 errors=remount-ro 0 1
/dev/sda1 /boot ext2 defaults 0 2
/dev/mapper/dhcppc0-home /home ext3 defaults 0 2
/dev/mapper/dhcppc0-tmp /tmp ext3 defaults 0 2
/dev/mapper/dhcppc0-usr /usr ext3 defaults 0 2
/dev/mapper/dhcppc0-var /var ext3 defaults 0 2
/dev/mapper/dhcppc0-swap_1 none swap sw 0 0
/dev/scd0 /media/cdrom0 udf,iso9660 user,noauto 0 0
/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0
from this point of view I realized that the cdrom mount point would be at /dev/scd0, then I issued the umount /dev/scd0 ... with no success .
after that time I issued the mount command :
well, with this command I found the mounting point in the last, for the most effective part I've been used these commands :
mount /dev/hdb /media/cdrom
with these two commands APT will realize that the mount point is the /cdrom/ and do not prompt you at the time , this is because debian will mount the cdrom at /media/[LABLE OF THE CD] .
I don't know how this problem is solved permanently but I think it should be an update for debian.