Re: uninitialized error

[moritz]

My guess is that a few of the input rows are simply not of the same syntax as the others (or some values are missing).

From your quite long post I didn't quite understand which value is undefined, but if you have identified it, do something like

use Data::Dumper;
$Data::Dumper::Useqq = 1;
# and then in the loop:
    unless (defined $value_that_is_sometimes_undefined) {
         print STDERR Dumper($whole_line);
    }

to see if the input line is still what you thought it was.