The first thing to do is make sure that your version of Perl was compiled with thread support.

The output from perl -V on my system includes the following lines:

C:\pwe>perl -V
Summary of my perl5 (revision 5 version 10 subversion 0) configuration
+:
  Platform:
    osname=MSWin32, osvers=5.2, archname=MSWin32-x64-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define,
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and also:

Characteristics of this binary (from libperl):
  Compile-time options: MULTIPLICITY PERL_DONT_CREATE_GVSV
                        PERL_IMPLICIT_CONTEXT PERL_IMPLICIT_SYS
                        PERL_MALLOC_WRAP PL_OP_SLAB_ALLOC USE_64_BIT_I
+NT
                        USE_ITHREADS USE_LARGE_FILES USE_PERLIO
                        USE_SITECUSTOMIZE
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Once you are satisfied that your Perl supports threads, you might want to compare your code with this snippet from one of my programs (which happily uses quite a few threads) and see if comparing it with your code might help.

foreach my $seq (0..$number-1)
{
  my $doneflag = \$play_done[$seq];
  $$doneflag = 0;
  $play_list[$seq] = threads->create(\&PlayoutThread,
                                      $doneflag,
                                      $target_list[$seq],
                                      $media_type,
                                      $portnum,
                                      $playouts);
  # Mark as already done if thread creation failed
  unless ($play_list[$seq])
  {
    $$doneflag = 2;
    $play_errors++;
  }
  # Count it if thread creation succeeded
  else
  {
    $started++;
  }
}
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