problems nebooting an iMac

[Christopher Cyll <Christopher.D.Cyll@williams.edu>]

I have an iMac I would like to netboot.  It has open firmware 3 on it.  I 
have a server set up with bootp and tftpd.  There is an entry in my bootptab 
for it like this:

my.domain.name:\
:ht=ether:\
:ha=0050E4960551:\
:sm=255.255.255.0:\
:ip=192.168.1.3:\
:hd=/tftpboot:\
:bf=yaboot:\
:bs=auto:

my /tftpboot directory contains:

yaboot
yaboot.conf
vmlinux

all are world readable.
In open firmware I use the command

boot enet:0

This works, the machine gets an ip, yaboot is retreived from my tftp server, 
and yaboot is loaded.  Here's where the problem shows up.

My screen shows this:

CLIENT: 0050e4960551 192.168.1.3
SERVER: 005004885ac2 192.168.1.2 stark
Transfer FILE: yaboot.conf
TFTP-actual=a6 TFTP-adler32=c79439b3 WARNING ! default_read called !
Error, can't read config file
WARNING ! default_close called !
Welcome to yaboot version 1.2.3
boot:

It seems that it can't retreive yaboot.conf.  Any one know how to fix that?  
All the documentation I can find on netbooting newworld macs seem to indicate 
that I should just put the yaboot, yaboot.conf, and my kernel in my /tftpboot 
folder and everything should work.

I'd appreciate any advice you can offer.  I'm not a member of this list so 
please cc me.  Thanks.

-Christopher Cyll