Got it now! Thank You !!!
The only inconvinience: I have to switch on 'network recognition' for my WLAN from within Win8PE manually to map network-drives of workgroup "MSHEIMNETZ" . . .
Is there a check-box for this in PENetwork/WinBuilder somewhere ?
With my new Win8PE-USB-Stick it's possible now to use this security-software for restorage reasonably:
http:// w w w.duplicati.com/howtos/how-to-install-and-run-duplicati-2-0-preview
. . . don't forget to activate . NET framework 4.5 . . .