Using SDL_SetWindowIcon is not working properley

Question

I am attempting to program a game engine using SDL and glew with picoPNG as an image loader. I was attempting to make a system to set the icon for the window in my Window class and something strange happened. It appeared the icon worked for some images and it didn't for others. I barely know anything about how SDL_Surface works so I used some websites to find some information. (I can't post links to them because I only have 8 out of 10 required reputation)

My code:

void Window::setWindowIcon(const std::string& filePath) {

    //read file
    std::vector<unsigned char> in;
    std::vector<unsigned char> out;

    unsigned long width, height;

    //Use my file loading class to read the image file
    if (DPE::IOManager::readFileToBuffer(filePath, in) == false) {
        fatalError("Failed to open " + filePath);
    }

    int errorCode = DPE::decodePNG(out, width, height, &(in[0]), in.size());
    if (errorCode != 0) {
        fatalError("Failed to decode png file!");
    }

    Uint32 rmask = 0x000000ff;
    Uint32 gmask = 0x0000ff00;
    Uint32 bmask = 0x00ff0000;
    Uint32 amask = 0xff000000;

    _sdlSurface = SDL_CreateRGBSurfaceFrom((void*)&out[0], width, height, 32, width * 4, rmask, gmask, bmask, amask);

    if (_sdlSurface == NULL) {
        std::cout << SDL_GetError() << std::endl;
        fatalError("Failed to create surface!");
    }

    SDL_SetWindowIcon(_sdlWindow, _sdlSurface);

    SDL_FreeSurface(_sdlSurface);
}

Finally, here are the two png files This one Worked. This one didn't.

The iteration through the code showed everything was fine and the only notification of an error was that the icon wasn't changing.

Edit: I have changed the color masks to be cross-Endian compatible

#if SDL_BYTEORDER == SDL_BIG_ENDIAN
                int shift = 0;
                rmask = 0xff000000 >> shift;
                gmask = 0x00ff0000 >> shift;
                bmask = 0x0000ff00 >> shift;
                amask = 0x000000ff >> shift;
        #else // little endian, like x86
                rmask = 0x000000ff;
                gmask = 0x0000ff00;
                bmask = 0x00ff0000;
                amask = 0xff000000;
        #endif

Answer 1

I think I found the answer. It appears that when I was using the alpha pixel, it took up 8 more bpp so I decreased the file size to 75x75 and the image worked.