Yes I'm sure I put it in the right way and if it was scratched it wouldn't have worked yesterday. Oh and I rented MP8 the other day and it wouldn't work so we returned it. I also restarted my Wii a couple of times too. Oh and you know how when you put in a disk it has like a title screen type thing in the disk channel? I put it and that appeared but it wouldn't work.
EDIT:Oh and just to clarify here's the title screen thing that I was talking about
How old is your Wii? If you've been using it too much, the disc-reading lens will get worn out. In fact, a dual-layered ISO can also play a factor in this stuff.