Hi Yigin,
please change your code logic as shown below, and see are you getting all your data during debugging.
SELECT
QALS~PRUEFLOS
QALS~CHARG
QALS~KTEXTMAT
QALS~AUFNR
QALS~ZZ_TUMANALIZ
QALS~PLNNR
QALS~ENSTEHDAT
QALS~MATNR
QALS~ENTSTEZEIT
QALS~OBJNR
QALS~LAGORTCHRG
QALS~KDAUF
MARA~MATKL
MARA~MTART
QASR~MERKNR
QASR~ZEITERSTL
QASR~CODE1
QASR~ERSTELLDAT
QASR~ORIGINAL_INPUT
QAPP~VORGLFNR
QAPP~PROBENR
INTO TABLE ITAB FROM QALS AS Q
LEFT OUTER JOIN MARA AS M ON Q~MATNR EQ M~MATNR
LEFT OUTER JOIN QAPP AS P ON Q~PRUEFLOS EQ P~PRUEFLOS
LEFT OUTER JOIN QASR AS S ON Q~PRUEFLOS EQ S~PRUEFLOS AND
P~VORGLFNR EQ S~VORGLFNR
AND
P~PROBENR EQ S~PROBENR