Validate publish invalid image

Getting a weird error when trying to validate. I have an image 75*75 for my driver.

× App did not validate against level publish:
Invalid image: /drivers/aquatemp/assets/images/small.png

Anyone seen this before and can help me?

Is the image the correct extension? Your code says PNG, the image uploaded to here is a JPG (/JPEG).

Had changed it but got it sorted. Thanks for quick reply.