Help: VFS: cann't open root device "hda2" or unknown-block(0,0)

["weiyun lv" <lvweiyun@hotmail.com>]

Hello, I have asked this question several days ago, now I meet it again in 
debian: when I boot the kernel I compiled I got this error message:

VFS: cann't open root device "hda2" or unknown-block(0,0)
Please append a correct "root=" boot option.
Kernel Panic -not syncing: VFS: Unable to mount root fs on unknown 
-block(0,0)
-----------------------------------------
the reason I wan to recompile the kernel is that I need to write a device 
driver for an IO card. Today I
1. download kernel source 2.6.10 from kernel.org
2. reconfig the kernel, disable module versioning, and enable most of 
kernel-hacking options.
3. use the following command to recompile and install the new kernel:
# make-kpkg clean
# make-kpkg --append-to-version=.0901 kernel-image
# cd /usr/src
# dkpg -i kernel-image-2.6.10.0901_10.00.Custom_i386.deb
4. after installation the menu.lst reads as following: ( kernel 2.6 boot 
with the above error message and kernel2.4 can boot successfully.)
===============
title Debian GNU/Linux, kernel 2.6.10.0901
root (hd0,1)
kernel /boot/vmlinuz-2.6.10.0901 root=/dev/hda2 ro
savedefault
boot

title Debian GNU/Linux, kernel 2.4.27-2-386
root (hd0,1)
kernel /boot/vmlinuz-2.4.27-2-386 root=/dev/hda2 ro
initrd /boot/initrd.img-2.4.27-2-386
savedefault
boot
==================

PS: 1. maybe something wrong with my kernel configuration and can anybody 
provide some material for this.
2. I use ext2 file system.