Strange IIgs error

[Noah Sager <noahsager@mac.com>]

It is my understanding that all you need to boot a IIgs is a properly 
formatted disk with "PRODOS" and "BASIC.SYSTEM" on it. I have booted 
by IIgs many times before but now, even an exact duplicate of the 
system 6 install disk gives me the error:

UNABLE TO LOAD PRODOS


This is really starting to bug me. What's wrong?

some info:

IIgs rom 1
1 meg ram
3.5 drive
5.25 drive

I create my disks on a PB180 and have not had trouble in the past.

I have consulted the FAQ and according to it (somewhere in section 8) 
my disks should work.

What's wrong?

Noah Sager
Omega84 Design
noahsager@mac.com