poj,

Thanks for the sample.

I modified your sample a little and was surprised with the results. See below: (Note: I have never used the 'in-units' before!)

   use strict;
   use DateTime;

   my $endDate = DateTime->new(
      year => 2015,
      month => 03,
      day => 30,
      time_zone  => 'America/New_York'
   );

   my $dt1 = DateTime->now( 'time_zone' => 'America/New_York' );
   my $dur = $endDate->subtract_datetime($dt1);

   my ($m,$w,$d) = $dur->in_units( 'months','weeks','days' );
   print "Expires in: $m months, $w weeks, $d days\n";

   ($w,$d) = $dur->in_units( 'weeks','days' );
   print "Expires in: $w weeks, $d days\n";

   ($d) = $dur->in_units( 'days' );
   print "Expires in: $d days\n";

__END__

Results:

Expires in: 1 months, 1 weeks, 3 days
Expires in: 1 weeks, 3 days
Expires in: 10 days
[download]

Could this be the source of the OP's discrepancies?

Regards...Ed