Bill of exchange tax code not defined; correct

What causes this issue?

The entered bill of exchange tax code is not defined.

System Response

Processing cannot be continued.

How to fix this error?

The error can have several causes. To eliminate the error, proceed as
follows:
RESET N1
Please check whether the desired bill of exchange tax code was
entered. Change it, if necessary
Procedure for the system administrator:
Please check whether the desired bill of exchange tax code is defined.
Ensure, if necessary, that it is defined. To do this, the bill of
exchange tax code is to be specified with a percentage rate.
IF &DEVICE& = 'SCREEN'
<DS:TRAN.OBA6>Proceed</>
ENDIF
Please check whether the default value is correct for the bill of
exchange tax code. If necessary, see to it that the default value is
changed.
IF &DEVICE& = 'SCREEN'
<DS:TRAN.OB73>Proceed</>
ENDIF

Error message extract from SAP system. Copyright SAP SE.