hi.
you can add user-exit at CMOD : ZXM08U04 . compare quantity , like this.
IF I_YDRSEG-TBTKZ <= ' ' AND I_YDRSEG-SHKZG = 'S'.
DATA: M_QTY1 LIKE I_YDRSEG-MENGE.
DATA: M_QTY2 LIKE I_YDRSEG-MENGE.
DATA: M_QTY3 LIKE I_YDRSEG-MENGE.
CLEAR: M_QTY1, M_QTY2, M_QTY3.
SELECT SUM( MENGE ) INTO M_QTY1
FROM EKBE
WHERE EBELN = I_YDRSEG-EBELN
AND EBELP = I_YDRSEG-EBELP
AND VGABE = '2' AND SHKZG = 'S'.
SELECT SUM( MENGE ) INTO M_QTY2
FROM EKBE
WHERE EBELN = I_YDRSEG-EBELN
AND EBELP = I_YDRSEG-EBELP
AND VGABE = '2' AND SHKZG = 'H'.
M_QTY1 = M_QTY1 - M_QTY2.
M_QTY3 = I_YDRSEG-BSMNG.
M_QTY2 = M_QTY1 + I_YDRSEG-MENGE.
IF M_QTY2 > M_QTY3.
MESSAGE 'Quantity invoiced greater than PO Quantity!' TYPE 'E'.
ENDIF.
ENDIF.
Michael.