9-patch drawable behaving badly, weird artefacts - what is wrong here?

Question

so Im trying out the 9-patch images. I started out with a PNG-file where I have a semi-transparent square with rounded corners:

Answer 1

Try to do 9-patch markings from all 4 sides. Also make sure you have .9.png file extension (f.i. your_cool_pic.9.png)

Here is my example