What I mean is, are you missing EVERY copy of game X or just X(JA)? Is it a range of games? ie, AbcX-AbdX. Since you know Solomon's Key isn't showing in GameEx, first look at the ROM file. How is it packaged? Is it like all the others? Second, are the ones around it showing, the range thing, or is it more sporadic? Maybe find a game with multiple version, such as X(USA) and X(JA), is it showing either?(Impossible to test unless you find another game that is missing, range thing again). I've never used ClrMAME, nor am I a huge MAME fan, but I know for things like Genesis and GameBoy, and N64 the ROMS come in many file types, .v64 .p64 .n64 .rom .zip... maybe gameex isn't seeing one of the file types. In windows if you sort the files by type then go to the top or bottom of explorer you should be able to compare the file types. See if Solomons Key is like the others.