error linking X11 lib

[Mário Olímpio de Menezes <mario@curiango.ipen.br>]

Hi,

	I'm trying to compile some programs (like example.c) from
imagemagick package, that require -lX11 option in gcc/g++ command line.
Every time I tried this, I get an error from ld not been able to find
libX11. But they are all installed.

	<root> linux1: ~# ldconfig -p | grep libX11
        libX11.so.6 (ELF) => /usr/X11R6/lib/libX11.so.6
        libX11.so.6 (libc4) => /usr/X11R6/lib/i486-linuxaout/libX11.so.6
        libX11.so.6 (ELF) => /usr/X11R6/lib/libX11.so.6
        libX11.so.6 (libc5) => /usr/lib/libc5-compat/libX11.so.6
        libX11.so.3 (libc4) => /usr/X11R5/lib/libX11.so.3

The error is:
gcc -O -I../inc -I/user/openwin/include -I/usr/X11R6/include -o
../bin/Linux/hierarchy hierarchy.c ../lib/Linux/libIM.a
../lib/Linux/libFFT.a ../lib/Linux/libjpeg.a -lm -L/usr/lib
-L/usr/X11R6/lib -L/usr/lib/X11 -lX11
ld: cannot open -lX11: No such file or directory

	What I'm doing wrong here? 
	Thanks,
[]s,
Mario O.de Menezes | "Many are the plans in a man's heart, but
IPEN-CNEN/SP       | is the Lord's purpose that prevails" Prov. 19.21