Boot problem update

I posted a message yesterday about a boot problem, this is just an 
update to that.

When I try to boot Gentoo I get the following message:

"VFS: cannot open device "sda4" or unknown-block(8,4)
please append a correct "root=" boot option
Kernel panic -not syncing: VFS: Unable to mount root fs on 
unknown-block(8,4)

<0> rebooting in 180 seconds.."

Is this a problem with yaboot.conf or because it is a kernel panic do I 
have to recompile?

On the advice of a Gentoo user of 2 years, my yaboot.conf now looks like 
this:

boot=/dev/sda2
device=hd:
partition=4
root=/dev/sda4
timeout=30
install=/usr/lib/yaboot/yaboot
magicboot=/usr/lib/yaboot/ofboot
image=/boot/kernel-2.6.11-gentoo-r2
    label=Linux
    read-only
    sysimage=/boot/System.map-2.6.11
    macosx=/dev/sda5
    enablecdboot
    enableofboot

However, this is largely unchanged from what I posted inline yesterday.  
Any help would be appreciated.  I have already recompiled my kernel, but 
I didn't know what changes to make.  It compiles okay I think.  The only 
change I made was to add Kaui and something else.  Really I get lost in 
the kernel options as they're not very verbose.  I don't intend to 
tinker with it in future.  This is probably where my problem is.  I 
followed the Gentoo handbook in setting it up, and a Dutch webpage 
<http://www.os3.nl/%7Evisser2d/g5install.html>.  I had to disable ADB 
support due to compile problems.

Thanks in advance,

Jon Lee