Your report calls the BAPI to change each selected order
... also it'possbile to test this BAPI using se37 transaction:
se37 -> Menu Function Module -> Test Sequences ->
BAPI_SALESORDER_CHANGE + BAPI_TRANSACTION_COMMIT -> Enter ->
Inform the data changed ->
Mark the required data to change in structures and internal tables that ends with letter X ->
F8 -> F3 -> F8 (BAPI_TRANSACTION_COMMIT)