I can't get this one texture to change in bioshock

i’ve been using special k with bioshock, and i’ve replaced a couple of texture so far, but the problem is i can’t replace the blood textures. i’ve been trying to turn it green, but when i find the texture and export it, edit it in paint.net, and put it in inject folder, it makes no difference when i reload the game. i don’t understand what i’m doing wrong, as other textures work in this game. i even made sure i exported to BC1 too. sorry, noob question.