Corrected URL name

netbox/templates/dcim/devicetype_list.html

@@ -6,7 +6,7 @@
 {% block content %}
 <div class="pull-right">
     {% if perms.dcim.add_devicetype %}
-        <a href="{% url 'dcim:device_add' %}" class="btn btn-primary">
+        <a href="{% url 'dcim:devicetype_add' %}" class="btn btn-primary">
             <span class="glyphicon glyphicon-plus" aria-hidden="true"></span>
             Add a device type
         </a>