Powerbook G3 (Pismo), won't boot YDL 4 cd1

[Stone]

I downloaded the ISOs from a mirror and using Disk Utility dragged over 
the images and click burn disc. The burning went perfectly and I can see 
the mounted disk under OS X. I then shut off my Powerbook with the cd 1 
in the drive, turn it on, hold down c and it boots to OS X. I tried 
zapping the P-RAM and also reset the nvram in open firmware.

Note: this is not the stock CD/DVD module that shipped with the 
Powebrook. That one is long dead and gone. This is a Toshiba drive, the 
same identical one used in other Powerbooks, which required absolutely 
no physical modification or software hacking in order to get it to work.

Might anyone have any suggestions?

Thank you,

baruch stone