hi,
the failure was in XF86Config-4 section of the keyboard
changed:
Option "XkbModel" "pc105"
to pc104, so that the section looks like:
Section "InputDevice"
Identifier "Keyboard0"
Driver "keyboard"
Option "CoreKeyboard"
Option "XkbRules" "xfree86"
Option "XkbModel" "pc104"
Option "XkbLayout" "de"
OPtion "XkbVarian" "nodeadkeys"
EndSection