[How to] PXE boot Server

[CrazyTSTer]

Can any one help me?
I want to load knoppix.6.2.ru.iso (size 700MB) with PXE
Because my /opt partition size iz 512MB i have made directory in /tmp/mnt/[my_usb_drive]/knoppix and extract where 3 files from knoppix.6.2.ru.iso(linux, minirt.gz and KNOPPIX)
my /opt/tftpboot/pxelinux.cfg/default is

display boot.txt
prompt 1
timeout 0
default Knoppix

label Knoppix
  kernel /tmp/mnt/[my_usb_drive]/knoppix/linux
  append ramdisk_size=100000 init=/etc/init lang=us apm=power-off vga=791 initrd=/tmp/mnt/[my_usb_drive]/knoppix/minirt.gz nomce noapic quiet boot_image=/tmp/mnt/[my_usb_drive]/knoppix/knoppix

label DSL
  kernel /dsl/linux24
  append ramdisk_size=100000 init=/etc/init lang=us apm=power-off vga=791 initrd=/dsl/minirt24.gz nomce noapic quiet boot_image=/dsl/knoppix

but it doesn't work

couldn't find /tmp/mnt/[my_usb_drive]/knoppix/linux

DSL Linux is booting up, but says

Can't find KNOPPIX filesystem, sorry.
Dropping you to a (very limited) shell.

why he says that?
what can i do to solve my problems?