Unable to get all my views

def nation_list(request):
    nations = Nation.objects.all()
    return render(request, 'soccer/nation_list.html', {'nations': nations})

def nation_detail(request, pk):
    nation = get_object_or_404(Nation, pk=pk)
    return render(request, 'soccer/nation_detail.html', {'nation': nation})

def league_detail(request, nation_pk, league_pk):
    league = get_object_or_404(League, nation_id=nation_pk, pk=league_pk)
    return render(request, 'soccer/league_detail.html', {'league': league})
Code for urls is below:

urlpatterns = [
    url(r'^$', views.nation_list),
    url(r'(?P<nation_pk>\d+)/(?P<league_pk>\d+)$', views.league_detail),
    url(r'(?P<pk>\d+)/$', views.nation_detail), 
]
Below is my league detail html code:

{% extends "layout.html" %}

{% block title %}{{ league.title }} - {{ league.nation.country_name }}{% endblock %}

{% block content %}
<article>
    <h2>{{ league.nation.country_name }}</h2>
    <h3>{{ league.title }}</h3>
    {{ league.content|linebreaks }}
</article>
{% endblock %}

Here is what i have for my models.py:

class Nation(models.Model):
    created_at = models.DateTimeField(auto_now_add=True)
    country_name = models.CharField(max_length=255)
    description = models.TextField()

    def __str__(self):
        return self.country_name

class League(models.Model):
    title = models.CharField(max_length=255)
    description = models.TextField()
    order = models.IntegerField(default=0)
    nation = models.ForeignKey(Nation)

    class Meta:
        ordering = ['order',]

    def __str__(self):
        return self.title