Programming Elixir - A Fibonacci Server

Hi, somehow, after typing code from book i managed only to make my code stuck at infinite loop. I did comparision side by side of my code to that i get from zipped examples i got with book (code from zip works ok). I can’t find where did i do mistake. Can anyone spot what did do wrong? I know i can move on, i understand what is going on, but it’s driving me nuts, beside, there is a big chance i won’t repeat that mistake if only i would know where it is

Anyway, here’s the code:

defmodule FibSolver do

  def fib(scheduler) do
    send(scheduler, { :read, self })
    receive do
      { :fib, n, client } ->
        send(client, { :answer, n, fib_calc(n), self })
        fib(scheduler)
      { :shutdown } ->
        exit(:normal)
    end
  end

  defp fib_calc(0), do: 0
  defp fib_calc(1), do: 1
  defp fib_calc(n), do: fib_calc(n-1) + fib_calc(n-2)
end

defmodule Scheduler do
  
  def run(num_processes, module, func, to_calculate) do
    (1..num_processes)
    |> Enum.map(fn(_) -> spawn(module, func, [self]) end)
    |> schedule_processes(to_calculate, [])
  end

  defp schedule_processes(processes, queue, results) do
    receive do
      { :ready, pid } when length(queue) > 0 ->
        [ next | tail ] = queue
        send(pid, { :fib, next, self })
        schedule_processes(processes, tail, results)
      { :ready, pid } ->
        send(pid, { :shutdown })
        if length(processes) > 1 do
          schedule_processes(List.delete(processes, pid), queue, results)
        else
          Enum.sort(results, fn {n1,_}, {n2,_} -> n1 <= n2 end)
        end
      { :answer, number, result, _pid } ->
        schedule_processes(processes, queue, [{ number, result } | results])
    end
  end
end

to_process = [37, 37, 37, 37, 37, 37]

Enum.each(1..10, fn num_processes ->
  { time, result } = :timer.tc(Scheduler, :run, [num_processes, FibSolver, :fib, to_process])
  if num_processes == 1 do
    IO.puts(inspect(result))
    IO.puts("\n #  time(s)")
  end
  :io.format("~2B     ~.2f~n", [num_processes, time/1000000.0])
  end)