BAPI_SALESORDER_CHANGE to update reason for rejection of sales order item

Hi,

The FM BAPI_SALESORDER_CHANGE is not working properly as I am getting below error when try to update the reason for rejection at sales order item level.

The delivery is done for this salesorder. Is it because the reason for rejection field is not as an input field when delivery done?

error in return table is " Field 'ABGRU' cannot be changed, VBAPKOM 000010 ready for input"

Request your suggestions to avoid this error.

Thanks