I've copied this from my /etc/inittab (SuSE). Compare you Deb to this, then try adjustments.
Code:
# # All scripts for runlevel changes are in /etc/init.d/. #
# This file may be modified by SuSEconfig unless CHECK_INITTAB
# in /etc/sysconfig/suseconfig is set to "no" #
# The default runlevel is defined here
id:5:initdefault:
# First script to be executed, if not booting in emergency (-b) mode
si::bootwait:/etc/init.d/boot
# /etc/init.d/rc takes care of runlevel handling #
# runlevel 0 is System halt (Do not use this for initdefault!)
# runlevel 1 is Single user mode
# runlevel 2 is Local multiuser without remote network (e.g. NFS)
# runlevel 3 is Full multiuser with network # runlevel 4 is Not used
# runlevel 5 is Full multiuser with network and xdm
# runlevel 6 is System reboot (Do not use this for initdefault!)
#
l0:0:wait:/etc/init.d/rc 0
l1:1:wait:/etc/init.d/rc 1
l2:2:wait:/etc/init.d/rc 2
l3:3:wait:/etc/init.d/rc 3
#l4:4:wait:/etc/init.d/rc 4
l5:5:wait:/etc/init.d/rc 5
l6:6:wait:/etc/init.d/rc 6
# what to do in single-user mode
ls:S:wait:/etc/init.d/rc S ~~:S:respawn:/sbin/sulogin
PS: you should be able to get into runlevel 3 by opening a term window and entering the command 'init 3'. By the same token, when in runlevel 3, you can get to runlevel 5 by using the command 'init 5'.