The compiler says it's expects a "string literal" but encountered a identifier. (Anyone explain what that means =) )
A "String literal" is just that. Something that is literally a string. Not a variable or constant that contains a string, but an actual string. Is this a bug/something to be fixed/ or am I useing the command in the wrong way?
Well the lower() bit seems to be a case of 'using it the wrong way'. Since you've supplied Incbin with a string literal, you already know the case of the filename. MacOS and Linux are potentially case-sensitive, thus it is adviseably to only use lowercase latin characters for filenames.