well then there is no way i can think of to solve this issue ... you need to determine either if the game is modified or not, or, which firmware has been installed in your xbox 360 drive ..
If you can get a DVD-ROM which can read that prototype game (by reading, i mean just detect the DVD, if it does not show the files or something, thats ok), then we can determine if the game was modified or not, and so you would know that you need the other type ..