Unable to change the skin in mobile

I am having trouble changing the skin in my mobile version of Minecraft. The error message reads "please import a .png type with 128x128,64x32 or 64x64", yet I am using a 128x128 skin file which is correct and works on my tablet. I have tried downloading both the final version and the beta versions, as well as clearing the cache and updating the app and phone, but the issue persists. I am sure the file is 128x128. I even tried cutting the image to 128x128 by myself and a site yet it still doesn't accept. Please help me as soon as possible. Thank you for your support.