V7/ knife trick?

[Valcor]

Hi all

I know the knife trick is frowned upon, but having bought a V7 PS2, I tried this trick with a CD game backup all of which had previously worked with my old V4, and it wouldn't work. I am not going to bother anymore (all negative threads about knife trick have scared me off), but out of curiousity - is it definately not possible to boot CD-R backup games with AR2 + knife trick