error dds

Hi I'm modifying a dds more exactly the icon_rapis.dds with the paint.net I add the new ones that I want and I keep it without touching anything like dds. I upload it to my data with the shaiya data file tool and I have the new changes, but I lose the icons of the skill and many more .. know pro that happens to me and how to solve it ..

Dds I edit it with paint.net but I can edit it with photoshop if necessary or gimp

Thank you