Shared object not found...

    Still strugling with my graphical interface.
    Now startx works fine. I tried to installed kdebase and
gnome-base ( 
I used the binary packages ). But "gdm" gives
"Shared object 
"libXdmcp.so.6" not found" and kdm
"Shared object "libX11.so.6" not found".
    This time I read the docs, but didn't see anything like
that.
    Any Idea ?
    Thanks.