PLEASE USE 'CONVERSION_EXIT_ALPHA_INPUT' BEFORE UPDATING FINAL TABLE.
eg.
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_INPUT'
EXPORTING
input = WA_FINAL-MATNR
IMPORTING
output = WA_FINAL-MATNR.
PLEASE USE 'CONVERSION_EXIT_ALPHA_INPUT' BEFORE UPDATING FINAL TABLE.
eg.
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_INPUT'
EXPORTING
input = WA_FINAL-MATNR
IMPORTING
output = WA_FINAL-MATNR.