Control the default Reverse Date at VL09

I want Reversal Date and Actual GI Date will be same Reverse Goods Movement (VL09). So I am going to set a popup message and checking for the date when user will click on Reverse button. 

Copy the standard program RVV50L09 to ZRVV50L09.
Go to line WHEN 'WAST' . (for Reverse button)
Add this code.

      IF xlikpukwa-wadat_ist NE  xlikpukwa-stdat.
        MESSAGE i000(fb) WITH 'Reversal Date & Actual GI Date should be the same.' .
        CLEAR sy-ucomm.
        sy-ucomm = 'MABL'.
        is_selfield-exit = gc_noout.

        PERFORM check_list_selection.

      ENDIF.