No input in serial console

[Niccolò Belli <darkbasic4@gmail.com>]

Hi, I'm using an RS232 serial console with Debian Lenny. Output works
fine (I can see the output since grub starts), but input doesn't (both
in grub and when it prompts for login).

Here is my /etc/default/grub:
[...]
GRUB_CMDLINE_LINUX_DEFAULT="quiet console=tty0 console=ttyS0,115200n8"
[...]
GRUB_TERMINAL="console serial"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8
--parity=no --stop=1"
[...]

and my /etc/inittab:
[...]
T0:23:respawn:/sbin/getty -L ttyS0 115200 vt100

Here is how I configured minicom in the client:
    | A -    Serial Device      : /dev/ttyS0
    | B - Lockfile Location     : /var/lock
    | C -   Callin Program      :
    | D -  Callout Program      :
    | E -    Bps/Par/Bits       : 115200 8N1|
    | F - Hardware Flow Control : No
    | G - Software Flow Control : No


Can someone help me?

Thank you,
Darkbasic