I wonder if someone could provide me with an explanation for the following:

(I have left in my debugging print statements.)

#!/usr/bin/perl -w
use strict;
use CGI ':standard';



my  $data="/path/data_add.txt";
my $checkthree = param('check');
my $num = param('num');
my $action = param('action');
my @line1 = ();
my @line_no = ();
my ($one,$two,$three,$four,$five);


print header(), start_html;


open (FILE,"$data") || die "whoops: $!";


while (my $line =<FILE>) {
    ($one,$two,$three,$four,$five) = split "\t",$line;
    if (($action eq 'Put') && ($three eq $checkthree)) {
    $five = $five + $num;
    print "we have $five on line $.<br>";
   @line1 = ($one,$two,$three,$four,$five);
    push (my @line_no, $.);
    print "Did this work @line_no<br>";
    last;
    }  elsif (($action eq 'Take') && ($three eq $checkthree)) {
     $five = $five - $num;
@line1 = ($one,$two,$three,$four,$five);
    push (@line_no, $.);
    last;    
        
    }       
     }
 
close FILE;

if  ($five < 0) {
print "message: can't do this";
  } else {
  my $line1 = join "\t", @line1;
  print "taking it out of the loop we have @line_no<br>";
  my $line_no = join " ", @line_no;
  print "we have $five on line $line_no<br>";    


open (FILE,"$data") || die "whoops 1: $!";
my @all=<FILE>;
close (FILE);

$all[$line_no-1] = $line1;


open (FILE2,">$data.tmp") || die "whoops 2: $!";
foreach my $line (@all){
$line=~s/\n//g;
print FILE2 "$line\n";}
close(FILE2);

rename("$data.tmp", "$data") || die "whoops 3: $!";

print "the field now contains: $five";
    }


print end_html();
[download]

My first question is:
having declared

my @line1 = ();
my @line_no = ();
[download]

I had expected both values to exit the loop - only @line1 does.
(The print statement in the loop shows that @line_no works properly there).
Why is it subsequently unseen, and what can I do to remedy this?
Thanks very much.