GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_ZTry loading them in a different order. It works on NVIDIA. It works on Intel. It's allowed by the OpenGL specification. It doesn't work on AMD/ATI last time I tried it. This is just one minor example of a case where AMD/ATI are broken with OpenGL, and this isn't with exotic new technology either. This is with a graphics hardware feature that dates back to the previous century and that is uniquitously supported.