I think you burned the ISO file to the CD as a normal file. Try thinking the other way while I explain. ISO files are complete CD's represented as a file on your harddisk. I don't use physical CD's anymore because I'm (physically) lazy . Instead I use a program that can emulate a CD drive.
Basically you need a program that can interpretate the ISO file and burn that "image" to a CD. Nero is fine at that in Windows while K3B is fine in Knoppix.
Hope it helps