Hi Yigin,
please change your code something like this, and see that still you are having problems.
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
INNER JOIN MARA AS M ON Q~MATNR EQ M~MATNR )
INNER JOIN QAPP AS P ON Q~PRUEFLOS EQ P~PRUEFLOS )
INNER JOIN QASR AS S ON Q~PRUEFLOS EQ S~PRUEFLOS )
WHERE P~VORGLFNR EQ S~VORGLFNR
AND P~PROBENR EQ S~PROBENR.
ENDSLECT.