Topic: GAMECUBE / LORD OF THE RINGS: RETURN OF THE KING QUESTION

I've recently been playing old Gamecube games through a Wii. However, when playing Return Of The King, for some reason, none of the upgrades I've purchased show up, regardless of which character I'm using. The Show Upgrades option is there when I pause that game, and the character's name is at the top of the screen when I select Show Upgrades, but beneath it is a black void. I've never seen this on a game before. Any suggestions on how to remedy this? I'm not a game geek by any stretch of the imagination, I've just been getting a kick out of being able to play old games I'd forgotten about. Could it be happening simply BECAUSE I'm using a Wii and not a GameCube console?
Any advice would be appreciated!
thanx!