linux - 自制镜像在虚机上可以自动按照ks.cfg配置安装，但是在物理机上读取不到ks.cfg文件，还是得一步步的手动安装，请大神赐教哈-PHP中文网问答

centos6.8的自制镜像在VMware虚机上可实现自动安装，是安装ks.cfg文件安装的。但是当我把镜像刻录到光盘上后，用服务器使用外置光驱安装时读不到镜像中的ks.cfg文件，还是得一步步的手动安装，这是怎么回事儿呢，请大神前辈们赐教啊！！！
ks.cfg:

#platform=x86, AMD64, or Intel EM64T
#version=DEVEL
# Firewall configuration
firewall --disabled
# Install OS instead of upgrade
install
# Use CDROM installation media
cdrom
repo --name="CentOS" --baseurl=cdrom:sr1 --cost=100
# Root password
rootpw --iscrypted $1$8wT06nMC$/xM8Ez3aSmHqjXpLPs6B60
# System authorization information
auth  --useshadow  --passalgo=sha512
# Use text mode install
text
firstboot --disable
# System keyboard
keyboard us
# System language
lang en_US
# SELinux configuration
selinux --disabled
# Installation logging level
logging --level=info

# System timezone
timezone  Asia/Shanghai
# Network information
network  --bootproto=dhcp --device=eth0 --onboot=on
# System bootloader configuration
bootloader --append="rhgb quiet" --location=mbr --driveorder="sda"
# Clear the Master Boot Record
zerombr
# Partition clearing information
clearpart --all --initlabel 
# Disk partitioning information
part / --fstype="ext4" --size=102400
part swap --fstype="swap" --size=16384

%pre
echo "Welcome to VICTOR'S WORLD!"

%post --nochroot
mkdir /mnt/source
mount -o loop /tmp/cdrom /mnt/source
cp -f /mnt/source/Packages/info2soft-ctrlcenter-6.0-9844.el6.x86_64.rpm /mnt/sysimage/root/

%post 
sed -i '/^id/s/3/5/g' /etc/inittab
service postgresql initdb
cd /root
rpm -i info2soft-ctrlcenter-6.0-9844.el6.x86_64.rpm
rm -f info2soft-ctrlcenter-6.0-9844.el6.x86_64.rpm

%packages
@base
@basic-desktop
@chinese-support
@core
@debugging
@desktop-debugging
@desktop-platform
@directory-client
@fonts
@general-desktop
@graphical-admin-tools
@input-methods
@internet-applications
@internet-browser
@java-platform
@legacy-x
@network-file-system-client
@office-suite
@print-client
@remote-desktop-clients
@server-platform
@server-policy
@workstation-policy
@x11
@php
@web-server
@postgresql
@postgresql-client
@info2soft
abrt-gui
certmonger
device-mapper-persistent-data
genisoimage
krb5-workstation
libXmu
mtools
oddjob
pam_krb5
pax
python-dmidecode
samba-winbind
sgpio
wodim

%end

isolinux.cfg：

default ks
prompt 1
timeout 60
SAY Valid option ks, local.

label linux
  menu label ^Install or upgrade an existing system
  kernel vmlinuz
  append initrd=initrd.img
label ks
  kernel vmlinuz
  append ks=cdrom:/ks.cfg initrd=initrd.img
label vesa
  menu label Install system with ^basic video driver
  kernel vmlinuz
  append initrd=initrd.img nomodeset
label rescue
  menu label ^Rescue installed system
  kernel vmlinuz
  append initrd=initrd.img rescue
label local
  menu label Boot from ^local drive
  localboot 0xffff
label memtest86
  menu label ^Memory test
  kernel memtest
  append -