Hello,
I've written too fast the name of the Dll but in my first post I wrote it good.
Thanks again to Phildu91
who helped to have the notify icon, It worked for me. My diamond runs on HTC Official ROM.
What I needed to do to have the good icon is to modify the notify.dll.0409.mui with the good icon and translate it in French with ResHack.
And then rename it notify.dll.040C.mui because in my case this is the one used by the mobile. And in order to use it, I use Resco Explorer (not free software) to copy it in the Windows directory, TC didn't let me do it because it's a Rom and system file.
VoilĂ* !
If it can help somebody...
Thanks again !