DBI->trace() looks like a good place to get some more information about what's going on.

I was puzzled by this:

  $count = 0 ;

  ....

  while($array = $sth1->fetchrow_array()) {
    $count++ ;
                
    if ($sth1->rows == 0) {
      print "No records matched for $ref\nn" ;
    }
    elsif ($count == 1) {
      $t = $array ;
      print "Entering taxID_format with $t\n" ;
      #&taxID_format($t) ;
    }
  }
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I find that $array = $sth1->fetchrow_array() fetches the next row, and sets $array to the value of the first field, or undef if no more rows. Leaving aside the possibility that a row may have an undef first column (or '0')... I don't see the purpose of the if ($sth->rows == 0). Further, I note that the documentation (http://search.cpan.org/~timb/DBI-1.607/DBI.pm#rows) says: "Generally, you can only rely on a row count after a non-SELECT execute ..., or after fetching all the rows of a SELECT statement.".

That said, unless the $sth->rows returns 0 (which is not what the documentation suggests), then the problem is elsewhere and some earlier operation is not doing what y'all expected.