Elixir - Randomized numbers in Agent

I'm trying to implement an Agent that behaves as a dice :

defmodule Dice do
  @on_load :seed_generator

  def start_link(opts \\ []) do
    Agent.start_link(fn -> [] end, name: __MODULE__)
  end

  def roll(n, val) do
    Agent.cast(__MODULE__, fn(_) ->
      Stream.repeatedly(fn -> :random.uniform(val) end)
      |> Enum.take(n)
    end)
  end

  def seed_generator do
    :random.seed(:erlang.now)
    :ok
  end
end

However, the generated numbers are the same, every time I restart iex. What am I doing wrong ? Is the seed not working because the :random.uniform call is inside the Agent ? Or something related with the Stream maybe.