Save a line. Instead of having set the error to a variable
insert authors (au_id)
values ('172-32-1176')
Select @iError=@@error
If @iError <> 0
Print 'Error' -- Do your error handling here
Try just
insert authors (au_id)
values ('172-32-1176')
If @@Error <> 0
Print 'Error' -- Do your error handling here