"Error, No DVD Found" in Gecko OS

[NapNap]

I'm trying to play Project: M (SSBB mod) in Dolphin, but after launching the .wad file, Gecko OS gives me the error "No DVD found." Brawl works fine when launched by itself. I have Brawl set as the default disc.

Can anyone help me figure out my issue?

Dolphin version: 3.0-458-dirty
CPU: Intel i5-2500K
GPU: GTX 460