NEED SNES EMU HELP "File is too highly compressed"

When I try to run 7zip packed snes games on Snes9x GX 4.2.4 for Wii I get an error message saying something along the lines of "File is too highly compressed"

The games that are in Winrar form load right up, and work flawlessly..

Examples of games that work: (all winrar)
Zelda - A Link to the past 691 KB
Super Mario All-Stars 954 KB

Examples of games that don't work: (all 7zip)
Donkey Kong Country 2,524 KB
Chrono Trigger 4,947 KB


Perhaps I'm missing some sort of file patcher or compiler for large files?

Any help is appreciated.