kernel panic: VFS: unable to mount root fs

["T.V.Gnanasekaran" <gnana@LanMinds.Com>]

hello,
I am trying to install kernel 2.2.12. I compiled as documented in the
README of the kernel source distribution.  I edited lilo.conf and exec
lilo and added. My root dev=/dev/sda3 (extend partition) boot=/dev/sda
But when I tried booting the new kernel, I got 

VFS: Cannot open root device 08:06
Kernel Panic: VFS: Unable to mount root fs on 08:06

what should I do now?

-gnana