I use a swedish layout in kde. No problems.
I changed the layout on the small icon left of the time (main kde screen).
The graphical login however I have us-keyboard layout...
I just looked in the /etc/X11/XF86Config-4 and found:
# May be changed with the KDE international keyboard tool.
XkbModel "pc104"
XkbLayout "us"

Mayby you have some kind of special keyboard?