I'm having a bit of trouble writing a module. My module has a function call "guid()". When I attempt to call it from my program, I get the following error:

Undefined subroutine &main::guid called at H:\bin\foo.pl line 11.
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However, if I call my function as Guid::guid(), it works. Here's the calling program that doesn't work:

use Guid;
print "Guid = " . guid() . "\n";
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Nor does this work:

use Guid qw(guid);
print "Guid = " . guid() . "\n";
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But, this does work:

use Guid;
print "Guid = " . Guid::guid() . "\n";
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Here's my module's header (from Guid.pm):

package Guid;
use strict;
use warnings;

use Math::BigInt;
use Net::Address::Ethernet qw(get_address);

BEGIN {
    use Exporter ();
    our ($VERSION, @ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS);
    $VERSION = 1.00;
    @EXPORT = qw(guid);
    %EXPORT_TAGS = ();
}


sub guid {
    my ($clockId, $netId) = $_;

    my $maxClockId = 2**14;
    my $clockIdOffset = 2**15;  #Turn on Clock High bit
    my $timeOffset = "122192928000000000";
    [...And On...]
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I've written Perl modules before and have successfully exported the various functions in them. I know the problem is probably something very simple, but I can't figure out what I am doing wrong. So, why can't I seem to export guid() to my main namespace? What stupid detail am I leaving out?