Looks like it does work, if this is what you expected:

#!/usr/bin/perl
use strict;
use warnings;
use Date::Manip;
$ENV{TZ} = 'PDT';

my $date1 = ParseDate('January 1, 2001 10:06AM');
my $date2 = ParseDate('January 31, 2002 10:00PM');

my $delta = DateCalc($date1, $date2); #, \$err);
print "\$delta             = $delta\n";

# Here's the $format
my $format = '%dh days %hd hours';
$delta = Delta_Format($delta, 2, $format);
print "\$delta (formatted) = $delta\n";
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Output:

C:\S\Test>dm.pl
$delta             = +0:0:56:3:11:54:0
$delta (formatted) = 395 days 11.90 hours
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