How to get header text in user exit for sales order

Hello all,

My requirement is that I get and modify the header text in user exit when creating a sales order. In the user exit I'll do some validation and put the error code into header text. But I can't use function 'READ_TEXT' to get header text since the text has not been updated into database.

Can anybody help me? point will be rewarded. Thanks in advance.

regards,

--Alex