Don't get how to do rounded edges at GUI!

Hi,

For a long time now I'm trying to create my own GUISkin. But there are a lot of problems. Especially at the using of rounded edges at all Sizes. I have this photoshop file:

This looks fine but when I apply these settings:

It looks like this later:

http://s14.directupload.net/images/120714/wou6kznn.png

(Sorry no more uploads possible)

So what should I do to create rounded edges in GUIBoxes? Why does this work with the pre-made GUI?