sum of binomials: not calculated?

Hello all,

Today, I was trying the following sum with Maxima:

bartv at eeklo:~/maxima$ maxima

Maxima 5.10.0 http://maxima.sourceforge.net
Using Lisp GNU Common Lisp (GCL) GCL 2.6.7 (aka GCL)
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
This is a development version of Maxima. The function bug_report()
provides bug reporting information.
(%i1) sum( binomial(s, k), k, 1, s);
                              s
                             ====
                             \
(%o1)                         >    binomial(s, k)
                             /
                             ====
                             k = 1

Apparently, the version of Maxima that I have does not calculate the
expression.

Maple seems able to do it:

bartv at vonneumann:~$ maple
    |\^/|     Maple 11 (IBM INTEL LINUX)
._|\|   |/|_. Copyright (c) Maplesoft, a division of Waterloo Maple Inc. 2007
 \  MAPLE  /  All rights reserved. Maple is a trademark of
 <____ ____>  Waterloo Maple Inc.
      |       Type ? for help.
> sum( binomial(s, k), k=1..s);
                                          s
                                    -1 + 2


Is there a way to find this same result with Maxima also?  I
really would like to start using Maxima for all my symbolic
calculations...

Thanks,
Bart

-- 
	"Share what you know.  Learn what you don't."