Hi Pramod,
try this code ....
Keep matnr and mblnr as first field in ur internal table.
SORT itab by MATNR and mblnr
Loop at itab.
if issued.
v_issued = v_issued+itab-menge.
elseif recepts
v_recept = v_recepts _ itab_menge.
When there is a change in matnr and mblnr
add the quantities into reqd internal table