DVD Mplayer

So I installed the Mplayer, and tried maybe 6 or 7 DVD's and all I get is the blue light of the disc flashes for maybe a second, I hear the disc turn, but nothing happens when I select dlib. I have a modded wii with wiikey2 running firmware version 3.2U. I found about this site through yahoo, so hopefully I will get some help in the matter.