This code works fine for me.

use strict;
use warnings;
use YAML qw(LoadFile);
use Data::Dumper;

# step 1: open file
open my $fh, '<', 'config.yml' 
  or die "can't open config file: $!";

# step 2: convert YAML file to perl hash ref
my $config = LoadFile($fh);
print Dumper($config), "\n";
[download]

Although I have my doubts this is the reason, you could try upgrading your YAML.

Note that YAML's own documentation recommends switching to YAML::XS.