I am able to open the file without a problem.

OK. (digging a little deeper...) What happens when you do something like:

#!/usr/bin/perl -w 
$|++;
use strict;
use warnings;
use diagnostics;

open(STUFF,"< containers.txt") or die "containters.txt:$!";
my @slurp=<STUFF>;
close STUFF:
chomp @slurp;
printf "%s\n",join(",",@slurp);
[download]

Are you seeing all your data?

Another (random) thought: Are you checking error codes from LDAP?