Copy of Tiger install DVD won't boot


I made a backup of my Tiger install DVD--I have always made a copy of the install CD's and used those rather than the original. The copy will not boot. In fact, it won't even mount. I'm using disk utility to create a CD/DVD master and then burning from it.

I haven't heard that the install DVD is copy-protected. Am I missing something obvious?
Basically, your way is the correct way and should work. Maybe it's just a bad DVD-R? Does it boot if you hold down the "c" key at startup?
The original install DVD works fine. I have also tried the direct copy method in Toast. The copied DVD does NOT work if the "c" key is held down at startup (nor does the copied disk even mound on the desktop, and won't mount with Disk Utility).
If it doesn't even mount on the Desktop, you can usually forget about booting from it. Really sounds like a bad medium...