It also is a bit tricky to make CDs bootable sometimes. I usually use Toast while booted in Mac OS 9 or earlier. This allows you to ensure that the system folder is blessed, and also I believe there may be a CD-ROM driver that the CD burning software must hide on the CD. (Not 100% sure on that one, though, all you may actually need is a blessed system folder.)

"Blessed" means that the system folder has the Mac OS icon on it.