[Koha] Authority error

After installing Authority files downloaded from SCIS via the bulkauthimport script on 3.8.3 using Debian packages, I get this error when attempting to 'choose' an entry for the 100$a field; Software error: Can't call method "subfields" on an undefined value at /usr/share/koha/intranet/cgi-bin/authorities/blinddetail-biblio-search.pl line 86. Other fields work without error. Google the error has not been helpful, Would someone kindly be able to point me in the right direction. Many, many thanks, Clint. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.