Help needed : icons not showing in WE and in game

Help needed : icons not showing in WE and in game

Hi !
Here is my problem.
1. When I saved my custom icon 64x64 of 32 bits, then converted it with wc3viewer, I was unable to see the new converted icon with wc3viewer.
2. When I saved my custom icon 64x64 of 24 bits, then converted it with wc3viewer, it said that I needed a white transparency (or something like that), so I said "YES" then I was able to see my custom icon with wc3viewer.
3. Though when I try to import it in World Editor, I can't see the hero custom icon I just did ! Either it shows white either it is invisible in the test.
4. In the Object Editor, when I try to select my custom icon, it is in the imported choices, but I don't see the picture of it...

I tried to custom the attack button too, but it shows invisible in the game...

What can I do to see my icons ? What did I do wrong ?!
Are there more things to change in the WE to have the icons working ?!

Thanks a lot !!!

Did you restart the World Editor?

Yes, of course...
Maybe my wc3viewer is wrong...
Like I said, I'm able to see with wc3viewer the 24 bits icons, but not the 32 bits icons.