Hi,
I have stuck at the first step of diskless boot in Scietific linux! So any idea is appreciated

I am using virtualBox on Windows 7 and I have installed a SL6.3 guest  as the server and another guest as the diskless client.

The server configs are

1)
# ls /var/lib/tftpboot/ -R
/var/lib/tftpboot/:
menu.c32  pxelinux.0  pxelinux.cfg  sl6 /var/lib/tftpboot/pxelinux.cfg:
default /var/lib/tftpboot/sl6:
initrd.img  vmlinuz


2)
# cat /var/lib/tftpboot/pxelinux.cfg/default
timeout 100
default menu.c32
menu title ########## PXE Boot Menu ##########
label 1
   menu label ^1) Install Scientific Linux 6
   kernel sl6/vmlinuz
   append initrd=sl6/initrd.img method=http://10.0.2.51/sl6 devfs=nomount
label 2
  menu label ^2) Boot from local drive
  localboot

3)
# cat /etc/dnsmasq.conf
no-resolv
no-poll
interface=eth2
domain=hpclab
expand-hosts
dhcp-range=10.0.2.52,10.0.2.100,static
dhcp-option=42,0.0.0.0
dhcp-boot=pxelinux.0
enable-tftp
tftp-root=/var/lib/tftpboot
dhcp-host=08:00:27:69:73:7A,ws04,10.0.2.52



Now when I start the client, I receive this error

CLIENT MAC ADDR: 08 00 27 69 73 7A GUID: EF720459-193C-4558-8C46-15FF790FCD1C
PXE-E51: No DHCP or proxyDHCP offers were received


As you can see below, both server and client have the same network type "Internal Network" and the same adapter "PCnet-Fast III". Please see the pictures
   http://i.stack.imgur.com/wapyf.jpg
   http://i.stack.imgur.com/XkRIc.jpg
   http://i.stack.imgur.com/amijN.jpg



What is the problem?
Regards,
Mahmood