Bug in the game laucher for new skin

Hi, today I create a new skin and i try to add it to my minecraft launcher, when i browse and select the skin file, I have a message from the launcher who says "Skin images must be 64*64 or 64*32 pixel PNG files", not sure of this, I looked if my skin file match with the data show. My skin has 64*64 pixel and it's a PNG files so I don't understand why I cant put it in my launcher ? Thanks in advance