You do not use fileevent. I constructed a simple toy server and client, they work just ok.

Server:

#!/usr/bin/perl

use IO::Socket::INET;
use IO::Select;

use strict;
use warnings;

my $listen = new IO::Socket::INET(Listen => 1, LocalPort => 8889);
my $sel = new IO::Select($listen);

{
  my $fh;
  print STDERR "1\n";
  sleep 1 until ($fh) = $sel->can_read;
  print STDERR "2\n";

  my $new = $listen->accept;
  $sel->add($new);
  print STDERR $new->sockhost," 2.5\n";
}

while (1){
  print STDERR "3\n";
  foreach my $fh ($sel->can_write){
      print STDERR "4\n";
      print $fh rand(100),"\n" or die "4:$!\n";
    }
  sleep 1;
}
[download]

Client:

#!/usr/bin/perl
use Tk;
use Tk::Listbox;
use IO::Socket::INET;

use strict;
use warnings;

my $top = MainWindow->new;
my $f = $top->Frame->pack;
my $lb = $f->Listbox()->pack;

my $socket = IO::Socket::INET->new(PeerAddr => 'localhost',
                                  PeerPort => 8889,
                                  Proto=>'tcp')
  or die "Cannot connect: $!\n";

$top->fileevent($socket,
               readable =>
               sub {
                 chomp(my $line = <$socket>);
                 print STDERR "$line";
                 $lb->insert('end',":$line");
                 # $lb->insert('end',$line) or die;
               });

MainLoop;
[download]

First, run the server. Then, run the client, it will connect to the server and it will start sending it numbers that will be shown in the listbox.