you are talking of original games or do you try to backup a backup ?
did any burned dvd was ever been played on that wii?
if not you can make sure if it is a newer chipset on your wii dvd drive by doing this:
Identify your Wii
put in your wii serial No. (sticker on the wiis back)
if you got a D3-v2 or D4 chip no burned dvd will ever be played on that wii.
other loaders can install your games to your drive too (also gx works for most people but causes problems from time to time, also no support provided anymore).
maybe have a look at cfg loader
Guide: Installing CFG Loader
or wiiflow (link below)