This could be a keyboard layout problem.
I would check that in KDE settings - I can't say where/how though as I don't use KDE that much.
In addition, if not already done I would do this as root:
cp /usr/share/X11/xorg.conf.d/90-keyboard-layout.conf /etc/X11/xorg.conf.d
Then edit /etc/X11/xorg.conf.d/90-keyboard-layout.conf to replace "us" by your locale in following line:
Option "XkbLayout" "us"
Then restart X or reboot.