boost::spirit - why won't this palindrome code work?

From: joshwaxman (JoshWaxman_at_[hidden])
Date: 2003-06-23 14:52:23

Hi.
I just started playing with spirit and tried the following code to 
match palindromes of strings consisting of a's and b's. Why won't 
this work? (It prints 0, not 1)

#include "boost/spirit/core.hpp"
#include <iostream.h>

using namespace boost::spirit;

int main(int argc, char* argv[])
{
        rule <> S;
        S =		ch_p('a')
                |	ch_p('b')
                |	epsilon_p
                |	('a' >> S >> 'a')
                |	('b' >> S >> 'b');

                
        
        char * str = "aabaa";	
        cout << parse(str, S).full;

        return 0;
}