@zodiark12 here's the sha1 and crc checks 2003+ is expecting. https://github.com/libretro/mame2003-plus-libretro/blob/f7e53fda8195ae9d9a2b33c1dbed27e7410a41ff/src/drivers/neogeo.c#L1574-L1589
You can compare the ones you have to these and double check your naming conversation. Make sure you done have ".rom.rom" or something like that either. Some desktops hide extensions. My guess is the check sum is off here for it not to include the file.