DataPeriod nefunguje dobře při použití P1Y

private function validatePeriodArrayYear()
    {
        $this->time->setTimestamp( self::$data['to'] );
        $year1 = $this->time->format('Y');
        $this->time->setTimestamp( self::$data['from'] );
        $year2 = $this->time->format('Y');

        $overlap = $year1 - $year2;

        if( $overlap > 0 ){

            $end = clone $this->time;
            $end->setTimestamp( self::$data['to'] );

            $interval = new DateInterval('P1Y');
            $period = new DatePeriod( $this->time, $interval, $end );
var_dump($period);
            $iteration = -1;
            foreach( $period as $onePeriod ){                var_dump($onePeriod);
                $iteration++;
                if( $iteration > 0 ){
                    $onePeriod->setDate( $onePeriod->format('Y'), 1, 1 );
                }
                $from = $onePeriod->getTimestamp();
                $onePeriod->setDate( $onePeriod->format('Y'), 12, 31 );
                $onePeriod->setTime( 23, 59, 59 );
                self::$data['zone'][$iteration] = array( 'from' => $from, 'to' => $onePeriod->getTimestamp()  );
            }

            self::$data['zone'][$iteration]['to'] = self::$data['to'];

        } else {
            self::$data['zone'][] = array( 'from' => self::$data['from'], 'to' => self::$data['to'] );
        }

    }

object(DatePeriod)[337]
  public start => 
    object(DateTime)[336]
      public date => string 2012-12-01 00:00:00 (length=19)
      public timezone_type => int 3
      public timezone => string Europe/Prague (length=13)
  public current => null
  public end => 
    object(DateTime)[48]
      public date => string 2014-01-13 23:59:59 (length=19)
      public timezone_type => int 3
      public timezone => string Europe/Prague (length=13)
  public interval => 
    object(DateInterval)[331]
      public y => int 1
      public m => int 0
      public d => int 0
      public h => int 0
      public i => int 0
      public s => int 0
      public weekday => int 0
      public weekday_behavior => int 0
      public first_last_day_of => int 0
      public invert => int 0
      public days => boolean false
      public special_type => int 0
      public special_amount => int 0
      public have_weekday_relative => int 0
      public have_special_relative => int 0
  public recurrences => int 1
  public include_start_date => boolean true

object(DateTime)[326]
  public date => string 2012-12-01 00:00:00 (length=19)
  public timezone_type => int 3
  public timezone => string Europe/Prague (length=13)

object(DateTime)[47]
  public date => string 2013-12-01 00:00:00 (length=19)
  public timezone_type => int 3
  public timezone => string Europe/Prague (length=13)