Well First Make Sure Its a PNG File, Second Rename It, Put The Name After The "Battle_" Part Cause Thats The Music Half, Third Make Sure Its In The Classic Pack Because Its The Main System... If It Still Doesent Work It Could Be Invalid, Corrupt, or Interlaced [Idk If Interlaced Affects It]
If It Was Made In Photoshop It Might Not Work, Open It In Paint on a Pc n Save It, But Before You Try These, Open The Editor again n Hover Your Mouse Over The Black Space On The Last Maps, The Thumbnail Might Be Blank