Page not found (404): django cannot match the path

I don't understand why I am getting a 4040 error while it seems I have defiend everything correctly. The Ticket model class has instances saved in the database so pk from 1 to 5 also exists. The html template is the simplest possible just to figure out why django cannot get and render the requested instance. Note that I can see the instances in the admin page and also other paths like adding new ticket etc are working fine. Any help is appreciated:

the path/page that I am trying to get:

http://127.0.0.1:8000/ticket/1/

app: urls.py

from . import views

urlpatterns = [
    url(r'^$', views.home, name='home'),
    url(r'ticket/<int:pk>/', views.ticket_detail, name='ticket_detail'),
]

project: urls.py

from django.conf.urls import url,include
from django.contrib import admin

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'', include('mmrapp.urls')), 
]

views.py

def ticket_detail(request, pk):
    ticket=get_object_or_404(Ticket,pk=pk)
    return render(request,'mmrapp/ticket_detail.html',{'ticket':ticket})

html

{% extends 'mmrapp/__l_single_column.html' %}
{% load static %}

{% block main_col %}
    <div class="ticket">
        <h2>Ticket: {{ticket.pk}}</h2>
    </div>  

{% endblock main_col %}