Gran Turismo Backup

[swalks]

HI there

I have a backed up copy of GT which works on an old Playstation, modell 550?? but the game wont work on a psone 102A.
Totally confused i am as it works on the early playstations but not on a psone. Both machines are modchipped and nero 5.5 was used to burn.

Any ideas would be appreciated.
cheers
simo