Capture Screen message while ME21N

Question

How can I capture the PO Number while executing Me21N.
In one report I am called ME21N. SAP Displays message PO <PO Number > Created. I want to capture the PO Number and wanted to do further processing.
I tried to get data from SYST MSGV1, MSGV2 MSGV3 MSGV3. But all variables are blank.
I cant use set and get parameters. Because if user exit PO creation without creating the PO then get parameter picks the last created PO number.
CALL TRANSACTION 'ME21N'.
EBELN = ???????

Answer 1

I have to Call Just ME21N and then user will create the PO mannually. after he saves the PO I want the PO number for further processing.
by using the following code I can Capture the PO number, but the problem is that it will behave like a BDC with differnet screen attribute.
Note i_BDCDATA table is blank.
DATA : EBELN TYPE EBELN.
CALL TRANSACTION 'ME21N'
USING i_bdcdata
MESSAGES INTO i_messtab.
*CLEAR i_messtab.
*SORT i_messtab DESCENDING by msgtyp.
*READ TABLE i_messtab  WITH KEY msgtyp = 'S'.
*IF sy-subrc = 0 .
EBELN = i_messtab-msgv2.
I just want to capture the screen value after ME21N.