I am using Archive::Zip and Archive::Zip::Tree for the first time and have come across a problem, and can't find any mention of it in the docs.

I have put the contents of directory C:\Windows\Desktop\carl\zip\mysql into an archive.
The contents consist of 1 file 'setup.exe', and 1 subfolder 'sub-folder' containing 1 file 'setup.bmp'.
I put all of this in a root folder named 'backup' within the archive.

However, after I run my script and check the contents of the archive, there is also a folder called 'C:' in the archive, with an empty directory structure within it.
Below is a representation of the archive directory structure, my expected structure, and then the script I used to create it.
Note: I have used 2 different zip utilities to check the contents of the archive and verify that the empty dir structure is really there.

Contents of test.zip

C:
->Windows
  ->Desktop
    ->Carl
      ->zip
        ->mysql
backup
->sub-folder
  ->setup.bmp
->setup.exe
[download]

What I expect it to look like:

backup
->sub-folder
  ->setup.bmp
->setup.exe
[download]

The script:

#!/usr/bin/perl
use strict;
use warnings;
use Archive::Zip qw/ :ERROR_CODES :CONSTANTS/;
use Archive::Zip::Tree;

my $dir = 'C:\Windows\Desktop\carl\zip\mysql';
my $file = 'C:\Windows\Desktop\carl\test.zip';
my $name = 'backup';

my $zip = Archive::Zip->new();

$zip->addTree( $dir, $name ) == AZ_OK
  or die("could not add tree");

$zip->writeToFileNamed( $file ) == AZ_OK
  or die("could not write file");
[download]