compiling svn-licq on kubuntu edgy?

Hi all

I'm trying to compile licq from svn on kubuntu edgy and I'm getting an 
error in configure of qt-gui. It complains about not being able to find 
the X11 include files (headers and libraries). I know kubuntu doesn't 
come by default with the files needed to compile stuff, but usually this 
can easily be fixed by installing packages. However I'm stumped this 
time, since I did install the libx11-dev package.

The exact error is:

(...)
checking for licq header files... "/home/simon/src/licq/include"
checking for X... no
configure: error: You need to have the X11 libraries and headers installed

~/src/licq/plugins/qt-gui$ ls -l /usr/X11R6/include/Xlib.h
-rw-r--r-- 1 root root 99001 2006-10-20 12:41 /usr/X11R6/include/Xlib.h

Any idea how to fix or get around this?

tnx

Simon