[Koha] link_bibs_to_authorities problem

Dear List, We imported a butch of bibs & a butch of authorities from koha 3.18.05 to koha 17.05, after using link_bibs_to_authorities.pl we have got such results Number of bibs checked: 5817 Number of bibs modified: 5701 Number of headings linked: 8406 Number of headings unlinked: 24019 Number of headings fuzzily linked: 0 BUT it isn't link correctly all headings, all authorities with the same "surname" but other "name" were linked together.(EX.: Abrahamyan Suren , Abrahamyan Armen, Abrahamyan Karen link to Abrahamyan Suren) So koha find only" Surname" for matching and link them. Pls help to solve this problem. Thanks, Erlanda