Game freezes upon loading stages with edited models?

[genandnic]

I've always been able to apply textures to stages, but anytime I try to install an entirely new stage to the game it freezes at the loading screen when I select it. I know I'm placing them in the correct location and under the right names, and I shouldn't need a .rel file unless I want to place the stage in a different location.

Stages such as Rainbow Road or Outset Island, the ones that have edited models won't work.
I'm using File Patch Code 3.5.1 to replace the stages in Gecko. Any clue as to why it might not be working?

Edit: This should probably be moved to Stage help eh?