X server can't recognize rgb(#, #, #) names from color browser

For some time, now, when I try to grab a color that doesn't match rgb.txt, I get an error.

% display --version
Version: ImageMagick 6.3.7 05/02/08 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2008 ImageMagick Studio LLC

% uname -a
Linux jag 2.6.24-1-amd64 #1 SMP Sat May 10 09:28:10 UTC 2008 x86_64 GNU/Linux

This is debian/lenny (testing).

I can browse colors as before, but if I pick an unnamed color, I get a popup with

============================
Color is unknown to X server
rgb(0,128,255)
============================

I don't know whether this is an X server issue, or an issue with imagemagick.

X.Org X Server 1.4.0.90
Release Date: 5 September 2007
X Protocol Version 11, Revision 0
Build Operating System: Linux Debian (xorg-server 2:1.4.1~git20080517-1)
Current Operating System: Linux jag 2.6.24-1-amd64 #1 SMP Sat May 10 09:28:10 UTC 2008 x86_64
Build Date: 18 May 2008  12:41:06PM

-- Mario