I think in this thread, you and me are the only ones who speak German, so asking the other guys to read your German posts is a little pointless.
Plus, to be honest, I find your German posts actually harder to parse than your English ones...

On the German forum you wrote that you are selecting all files via ctrl+alt, but I guess you meant to say via ctrl+a.
As ken has said, aMule behaves absolutely like it should. And if you want to have no item selected, you can simply do a control-click on the remaining selected item to unselect it.