File::Find preprocess difficulties

Fastolfe has asked for the wisdom of the Perl Monks concerning the following question:

I am attempting to use File::Find to recurse down a dated directory structure and yell when it finds a certain (the "latest") path/filename within that structure (at the 'year', 'month' or 'day' level).

Running this script with an argument of /path/content, for example, should recurse down a directory tree and print out:

2002/07/14/path/content
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if it's able to locate path/content (with any file extension) within the 2002/07/14 directory.

The trick here is that I need the testing done such that the most recent dates are checked first (year 2002 tested before 2001, month 12 checked before 11). The File::Find::Unix man page would seem to indicate that all I need to do is specify a 'preprocess' function to do my sorting. My preprocess function is not getting called and I'm at a loss as to why. The script I'm using appears below (it's small).

use strict;
use File::Find;
use File::Spec;

my $search = File::Spec->canonpath("/".shift());
1 while $search =~ s!/[^/]+/\.\./?!/!;
$search =~ s!^/!!;

find({
 wanted => \&wanted,
 preprocess => \&preprocess,   # this should do it
 follow => 1,
}, ".");

sub wanted {
 return unless -d;
 print "testing $File::Find::name\n";    # see these fine
 if (glob("$_/${search}.*")) {
  print "$File::Find::name/$search\n";
  exit;
 }
}

sub preprocess {
 print "pre-processing @_\n";    # never see this
 return sort { $b <=> $a } grep { /^\d+$/ } @_;
}
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Output:

[fastolfe@home test]$ ./resolve-name /path/content
testing .
testing ./2001
testing ./2001/05
testing ./2001/05/30
./2001/05/30/path/content
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Unfortunately the one it found was actually the oldest, which might imply that it's following a standard ascending sort that one typically sees on Unix.

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