Sum with Distinct misbehaving

[JustinDallas]

Hello Folks,

I'm working with some script, and for some reason, when I perform a load with a Sum after a Distinct, it comes back with the wrong number.  Below is the INCORRECT version of the script which gives me 8 usage days:

TractorUsageDatesBroken:
LOAD tractor_id,
tractor_id & '\' &  MONTH(lgh_date) & '\' &   YEAR(lgh_date)  AS 'tractor_usage_key',
SUM(Iterate) AS 'tractor_usage_days',
YEAR(lgh_date) AS 'lgh_header_year',
    MONTH(lgh_date) AS 'lgh_header_month'
GROUP BY tractor_id, YEAR(lgh_date), MONTH(lgh_date)
;
LOAD DISTINCT tractor_id, lgh_date, Iterate
;
LOAD tractor_id, Date(start_date + IterNo() - 1) AS 'lgh_date', 1 AS 'Iterate'
WHILE start_date + (IterNo() - 1) <= end_date
;
LOAD tractor_id, Date(start_date_text) AS 'start_date', Date(end_date_text) AS 'end_date'
;
LOAD * Inline
[
  'tractor_id', 'start_date_text', 'end_date_text',
  '17003', '03/01/2018', '03/02/2018',
  '17003', '03/02/2018', '03/03/2018',
  '17003', '03/05/2018', '03/06/2018',
  '17003', '03/06/2018', '03/07/2018'
]
;

Below is the CORRECT version of the script which gives me a correct 6 days of usage.

Qualify *
;
TractorUsageDatesCorrect:
LOAD DISTINCT tractor_id, lgh_date, Iterate
;
LOAD tractor_id, Date(start_date + IterNo() - 1) AS 'lgh_date', 1 AS 'Iterate'
WHILE start_date + (IterNo() - 1) <= end_date
;
LOAD tractor_id, Date(start_date_text) AS 'start_date', Date(end_date_text) AS 'end_date'
;
LOAD * Inline
[
  'tractor_id', 'start_date_text', 'end_date_text',
  '17003', '03/01/2018', '03/02/2018',
  '17003', '03/02/2018', '03/03/2018',
  '17003', '03/05/2018', '03/06/2018',
  '17003', '03/06/2018', '03/07/2018'
]
;


TractorUsageDatesCorrect2:
LOAD TractorUsageDatesCorrect.tractor_id,
TractorUsageDatesCorrect.tractor_id 
    & '\' &  MONTH(TractorUsageDatesCorrect.lgh_date) 
    & '\' &   YEAR(TractorUsageDatesCorrect.lgh_date)  AS 'tractor_usage_key',
SUM(TractorUsageDatesCorrect.Iterate) AS 'tractor_usage_days',
YEAR(TractorUsageDatesCorrect.lgh_date) AS 'lgh_header_year',
    MONTH(TractorUsageDatesCorrect.lgh_date) AS 'lgh_header_month'
Resident TractorUsageDatesCorrect    
GROUP BY TractorUsageDatesCorrect.tractor_id, 
YEAR(TractorUsageDatesCorrect.lgh_date), 
        MONTH(TractorUsageDatesCorrect.lgh_date)
;


DROP Table TractorUsageDatesCorrect
;

I know DISTINCT can be strange in the Qlik world, but I'm not sure why it's giving me the wrong number.

Any help is greatly appreciated.