Do you have a section that looks like this in /etc/inittab ? (this one is from gentoo, it's a bit different on debian)
Code:
c1:12345:respawn:/sbin/agetty 38400 tty1 linux
c2:2345:respawn:/sbin/agetty 38400 tty2 linux
c3:2345:respawn:/sbin/agetty 38400 tty3 linux
c4:2345:respawn:/sbin/agetty 38400 tty4 linux
c5:2345:respawn:/sbin/agetty 38400 tty5 linux
c6:2345:respawn:/sbin/agetty 38400 tty6 linux
If you have it, look at the numbers : in my example, in runlevel 1, only the first tty will be launched. Maybe you boot in the wrong runlevel.
I boot in runlevel 3 by default :
You can try another runlevel without rebooting : as root type :
where # is the runlevel you want to switch to.