When I found a THIRD copy of my normal David's Adventure cartridge I put it in my N64 and the cable that I used to finish OperationCode64 into my computer. When I inserted a code I got from a friend I inserted it. First, the game started glitching out, then the boss was not present (look in the fail ending project so you know who the "boss" is), then I got this screen.
This Appears On The Gamecube Release Of David's Adventure.