.desktop file does not work correct on Raspian

[Volker Dirr]

Under Rasbian on my Raspberry Pi, the .desktop file does not work correct.
Name, translation and comments work fine.
But Exec and Icon does not work.
for example this work well, but it is a bad style of course:
Icon=/home/pi/Downloads/fet-5.26.1/icons/fet.png

But this does not work:
Icon=fet
Icon=/fet
Icon=./fet
Icon=fet.png
Icon=/fet.png
Icon=./fet.png
Icon=icons/fet.png
Icon=/icons/fet.png
Icon=./icons/fet.png
Icon=/home/pi/Downloads/fet-5.26.1/icons/fet

Any idea how to fix it?
Similar problem with Exec. Or is that a Raspian bug?

[Volker Dirr]

Oh... Sorry. I forgot to write "make install". Icon and exec work well then.