Don't post in all possible topics, be patient.
There is nothing wrong with your image, except that it is not a standard size (1280x786, should be x720). And, it's just that one picture isn't enough for you. With androids, it works much differently. You can, possibly, place it in the xhdpi subfolder in adequate ux (depends on the resolution of your screen) so that there is only one.
What you most likely do wrong is packaging of zip file (compression, structure...)