Try to update.

On a newer Perl version it looks fine, even without setting locale parameter:

% perl /tmp/scratch.pl  
2015-08-24T17:36:47

% perl -v

This is perl 5, version 20, subversion 2 (v5.20.2) built for x86_64-linux-gnu-thread-multi
...

% dpkg -l|grep libdatetime.*perl
...
ii  libdatetime-perl                              2:1.20-1 
ii  libdatetime-locale-perl                       1:0.46-1
...

/tmp/scratch.pl contains:

use warnings;
use strict;

use DateTime;

# [faked method call]
print MakeDateTime(undef, 2015, 8, 24, 17, 36, 47, 144);

sub MakeDateTime {
  my $self = shift;
  my ($Year, $Month, $Day, $Hour, $Minute, $Second, $MilliSecond) = @_
+;

  my $DateTime = DateTime->new(
    year       => $Year,
    month      => $Month,
    day        => $Day,
    hour       => $Hour,
    minute     => $Minute,
    second     => $Second,
    nanosecond => ($MilliSecond * 1000000),
    time_zone  => 'America/New_York',
  );

  return $DateTime;
}
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