I'd like to activate ctrl+alt+backspace on multiple pcs (Ubuntu 14.04) using

dpkg-reconfigure keyboard-configuration

I don't want to do the dialog every time so i tried:

debconf-get-selections | grep "^keyboard-configuration" > config.dat

on a host where i answered the dialog with the desired answers

On the host where i want to do it non interactively i tried:

debconf-set-selections config.dat

dpkg-reconfigure -f noninteractive keyboard-configuration

it ran without asking, but afterwards the selections where reset to the default values

How can i get dpkg to use my predefined values? Or is there another possibility to enable the ctrl+alt+backspace for all users without going through dialogs?