Ok, just ran the program over here with out any modifications and it works for me....

I made a few small ajustments to make it little bit simpler to see whats going on and I used strict and warnings (should always do that).

Just for your info I am using: perl v5.8.0 built for i386-linux-thread-multi

#!/usr/local/bin/perl -w

use strict;

open(IN, '<', "test_file.txt");
my %fvalues;
while(<IN>){
    if (/(.*) (.*)/){
        $fvalues{$2} = $1;
        print " While : $fvalues{$2}\n"; # this one prints
    }
}

for(my $counter = 1 ; $counter < 6 ; $counter++){
    print " For   : $fvalues{$counter}\n" ; # no output
}
close(IN);
[download]