Try a different disc maker, and also try both DVD-R and DVD+R type discs, could be that the laser is worn on the mk4...

Does the drive read a non modded backup?

__________________
Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.