Problem : Even After Showing Message into PO Message list PO is Getting save on BACK , EXIT buttons
Solution :
Thats Work for me too ..
Exit name : MM06E005 ( Customer fields in purchasing document )
Function module : EXIT_SAPMM06E_012 ( Check Customer-Specific Data Before Saving )
INCLUDE : ZXM06U43 .
*&---------------------------------------------------------------------*
*& Include ZXM06U43
*&---------------------------------------------------------------------*
DATA bg_exd TYPE c.
IMPORT bg_exd = bg_exd FROM MEMORY ID 'BG_EXD'.
IF bg_exd EQ 'X'.
MESSAGE e375(po) WITH 'Po Release amount is Exceeding than remaining budget !!!'.
ENDIF.
*&---------------------------------------------------------------------*