BADI IF_EX_WORKORDER_UPDATE~BEFORE_UPDATE - Stop Process Order from Saving

Hi,

I am using BADi as below to check material list in transaction 'COR1',

IF_EX_WORKORDER_UPDATE~BEFORE_UPDATE

I want to give error message on certain condition in this exit,but it gives dump if you give error message.

Please let me know if there is any way to stop process order from saving at this point?

You help will highly be appreiciated.

Regards,

Sanjeev