BAPI_SALESORDER_CHANGE not handle message type W

Hi,

I tried to update custom field in Additional Data B of sales order with BAPI_SALESORDER_CHANGE. BAPI calls USEREXIT_CHECK_VBAP. This user exit does a validation on custom field and return message type W when validation failed. BAPI immediately errored out and program was terminated (as if message type A).

Why BAPI not handle message type W?

Any help is appreciated. Thanks.

Best Regards,

Dominic