Gaming rp maker xp white line problem

[Dominator211]

hi im making a pokemon game with rpg maker xp and most of tilesets arent completed so i thought id add to them myself but after i made one little change the was this white outline that wasnt there before and this is bugging me does anyone know how to fix this...?


ive attached a picture below
i have a two montoir setup and to this right is the tiles ive added to the tileset