Training Stream - Extending the Editor - Jan. 20th, 2015

Can you explain it to me?
I took example style file from Paper2D, set ClassIcon and ClassThumbnail, then call FClassIconFinder::RegisterIconSource(StyleSet.Get());
But in the Editor I have white squeres instead of icons. Icons in the right place, and path is right (I cheked it in debbuger).

http://s21.postimg.org/pvddnjm13/image.png

http://s3.postimg.org/xo5xkodzn/image.png

What did I do wrong?