backups not working

[DutchDemon]

i got a v7 with a matrix infinity, installed it myself. it boots up fine, but only my originals are working. i've tried backups of ps2 (colin mcray rally and burnout 3) and ps1 (ape escape), but they dont work. only my originals.... i guess i did something wrong, but i have no idea what..
i burned the ps2 dvd discs with nero, but i dont think that that's the problem, because my backed up ps1 games used to work on my ps1...
any advice?

edit: o yeah, im using princo dvd-r (yeah i dont know either :P). anyone knows if those are fine?
another o yeah, i do get the infinity logo when i boot the ps2 originals