Thanks for the test project.
After looking at your code I did realize what I had wrong, same thing you told me earlier but I did not realize that the name of that static function also matters in this case.

My Xaml was correct, My dependancy property name was correct But the name of the static functions, as you said was incorrect. As I said, I did not knew it matters in this case because I though it was just a... name for that function

Thanks for your help with this Sfernandez and sorry for all this hassle which I managed to cause with my lack of understanding what I read

Thanks a lot for reporting back!