xbox .iso's

[newby]

I recently got to hand-on to experiment in copying xbox games following some many tutorias available around the net.

1) I managed to successfully prepare a revolutionx boot cd, and set the network for the modded xbox from there.
2) The game cd data structure was extracted over the network to a location on the PC w/ an ftp client program.
3) And finally an .iso from the game data was prepared & burned w/ xiso (v1.5) & prassiprimo

but... i could not manage the backup to run
if the game data .iso was prepared the same way as the evolutionx cd, why doesn't it run? Is there any copyprotection involved? -- The game is "return to castle wolfstein".

* Does the evolutionx console has to be (installed) load from the xbox HD for the backups to work??
* Do i need to flash the modchip for the backups to work? As the modchip bios version is recognized as unknown.
* Are there any "good" or "bad" media brands for backups?


any light on the subject would be appreciated.