物料卡控问题

Tables: RESB.
Data: ZQTY like mseg-menge.
If I_MSEG-BWART = '261' and I_MSEG-RSNUM <> ' '.
Select * from RESB where rsnum = I_MSEG-RSNUM and
RSPOS = I_MSEG-RSPOS and
Matnr = I_MSEG-Matnr.
If SY-SUBRC = 0.
ZQTY = ( RESB-BDMNG - RESB-ENMNG ).
If I_MSEG-Menge > ceil( ZQTY ).
MESSAGE E002(Z001) with I_MSEG-MATNR.
Endif.
Endif.
Endselect.
Endif.
在EXIT_SAPMM07M_001里面，做领料保存时提示，现在如图这种做法，无法卡控
求大神帮忙，要怎么搞？？？？？？？？？？